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3|| JQ- BUILD A STUN GUN 




L4d 



$1.95 SEPT. 1986 

IN CANADA $2.50 




ECHNOLOGY - VIDEO - STEREO - C^ 

THIS STUN GUN 

asy-to-build 
electronic protection 

OMMUNICATIONS 

rom DC to microwave 



as - SERVICE 



GERHSBACK 



V DESCRAMBLING 

•ractical PLL circuits 



HE WORLD 
IBOVE 800 MHz 

lew regulations and services 

)SCILLATORS 

design your own 



FROM BRAINSTORM 
TO BREADBOARD 

How to design electronic projects 



o "71896 ll 48783 l i 





PLUS: 



x video News 

* Satellite TV 

* PC Service 

* Antique Radios 

* Robotics 

* ComputerDigest 



TEK 



2236 100 MHZ 
OSCILLOSCOPE 



THE ANSWER 
BY ANY MEASURE 



100 MHz scope, counter, timer, 
multimeter: All one integrated system 



100 MHz dual 
time base scope. 

3.5 ns risetime; 
sweeps from 0.5 s 
to 5 ns/div; alter- 
nate sweep; ±2% 
vertical/ horizontal 
accuracy; vert- 
ical sensitivity to 
2 mV/div @ 
90 MHz. 



9-di git fluores- 
cent display. 

Digitally accurate 
readouts accom- 
pany the CRT 
waveform. Error 
messages and 
prompts also 
appear on the 
display. 



Dc volts and ac 
coupled true 
RMS volts. Mea- 
sured through the 
Ch 1 scope input. 



Gated measure- 
ments. Use the 
scope's intensified 
marker to measure 
frequency, period, 
width and to count 
events within 
specified portions 
of the signal. 



Auto-ranged, 
auto-averaged 
counter/timer. 
Frequency, period. 

width, delay time, 
A-time, plus total- 
ize to more lhan 
8 million events 
—with 7 digits 
plus exponent 
displayed. 



Auto-ranged 

D MM. Use floating 
DMM side inputs 
with up to 5000- 
count resolution. 
Get precise read- 
outs of average dc 
and true RMS volt- 
age. Measure 
resistance from 
milliohms to 
gigohms. 




Now make measurements 
faster, easier, with greater 
accuracy and user confidence. 

The Tek 2236 makes gated coun- 
ter measurements, temperature, 
time, frequency, resistance and 
voltage measurements push- 
button easy. You see results con- 
currently on the 9-digit numeric 
readout and CRT display. 

its complete trigger system 
includes pushbutton trigger view, 
plus peak-to-peak auto, TV 
line, TV field, single sweep and 
normal modes. 



At just $2650: the 2236 
includes the industry's first 3-year 
warranty on all parts and labor, 
including the CRT. 

Integrated measurement 
system. 3-year warranty. 15- 
day return policy. And expert 
advice. One free call gets 
it all! You can order, or obtain lit- 
erature, through the Tek National 
Marketing Center. Technical per- 
sonnel, expert in scope applica- 
tions, can answer your questions 
and expedite delivery. Direct 
orders include probes, operating 



manual, 15-day return policy, full 
warranty and worldwide service 
back-up. 

Order toll-free: 
1-800-426-2200 
Extension 57 

In Oregon call collect: 
(503) 627-9000 Ext. 57 
Or write Tektronix, Inc. 
P.O. Box 1700 
Beaverton, OR 97075 



Tektronix 

COMMITTED TO EXCELLENCE 



CopyriQMiD1984.Teklromit.lnc All rights res«trued TTA-324-1 'U.S Domestic puce FO B Beaverton. Oreaon Price subject lo change 

CIRCLE 92 ON FREE INFORMATION CARD 



SepTEIVlbER '86 



Electronics 



Electronics publishers since 1908 



Vol. 57 No. 9 



SPECIAL 


45 


COMMUNICATIONS: FROM DC TO 


RADIO 


SECTION: 




MICROWAVE 

Take a guided lour through the 
communications spectrum. 
Josef Bernard 


88 


ANTIQUE RADIOS 

Antique headphones and 
speakers and how to 
troubleshoot them. 




49 


THE NEW WORLD OF COMMUNICATIONS 

A look at the world above 800 MHz, and the 




Richard D. Fitch 






new regulations and services you'll be seeing. 


84 


COMMUNICATIONS 






Benn Kobb 




CORNER 

Transmitters Vs. Receivers: 
the war overRFi 


BUILD THIS 


41 


STUN GUN 








Protect yourself with 75,000 volts. 




Herb Friedman 




44 


Robert Grossblatt and Robert lannini 
PHONY BURGLAR ALARM 








COMPUTERS 






This "electronic scarecrow" makes your house 
look like it's protected with hi-tech 
electronics. Michael Ringenberger 


Following 
page 72 


COMPUTER DIGEST 

CB scanners, souped-up 
PC's and optical-disk 
technology. 




69 


PC SERVICE 

Use our exclusive direct-etch foil patterns to 
make circuit boards for this month's projects. 






EQU 
RE PC 


IPMENT 


TECHNOLOGY 


6 


VIDEO NEWS 


>RTS 






Inside the fast-changing video scene. 


24 


Soar Model 3430 






David Lachenbruch 




DMM 




72 


SATELLITE TV 










Test equipment for satellite TV. 


32 


Vector SMT 






Bob Cooper, Jr. 




Training Kit 




61 


FROM BRAINSTORM TO BREADBOARD 

The smart way to design electronics projects. 








DEPARTMl 






David J. Sweeny 








74 


ROBOTICS 


114 


Advertising and 






Position sensors for robots. Mark J. Robillard 


114 


Sales Offices 


CIRCUITS AND 


54 


TV SIGNAL DESCRAMBLINC 


Advertising Index 


COMPONENTS 




Part 4. Practical descrambling circuits using 


12 


Ask R-E 






PLL's. William Sheets and Rudolf F. Graf 




58 


HOW TO DESIGN OSCILLATOR CIRCUITS 

Part 3. A look at R-C oscillators. Joseph J. Carr 


115 


Free Information 
Card 




64 


THE VERSATILE 4007 








It may be the world's most versatile CMOS IC. 


14 


Letters 






Ray Marston 


95 


Market Center 




78 


SERVICE CLINIC 










Customer psychology for servicing TV's. 


34 


New Products 






Jack Darr 


4 


What's News 




78 


SERVICE QUESTIONS 

Solutions to servicing problems. 








92 


DRAWING BOARD 

Correct that software! Robert Grossblatt 







RADIO-ELECTRONICS, (ISSN 0033-7862) Sept., 1986. Published monthly by Gernsback Publications. Inc.. 50C-B Bi-Counly Boulevard. Farmmgdale. NY 1 1735 Second-Class Poslage paid al 

Farmingdale. NY and additional mailing offices. Second-Class mail registration No. 9242 aulhorized at Toronto. Canada. One-year subscription rate U.S.A. and possessions 516.97. Canada 

S22.97. all olher couniries S25.97. Subscription orders payable in US funds only, international postal money order or chock drawn on a US A. bank. Single copies SI ,96.©t98€ by Gernsback 

Publications, Inc. All righls reserved. Printed In U.S.A. 

POSTMASTER: Please sand address changes to RADIO-ELECTRONICS, Subscription Dept.. Bon 55115. Boulder, CO 80321-5115. 

A stamped self-addressed envelope musl accompany all submitted manuscripts and or artwork or photographs il their return is desired should Ihey be rejected We disclaim any responsibility for the 

loss or damage ol manuscripts and or artwork or photographs while in our possession or otherwise. 



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Cover 1 




We certainly hope you don't run into the 
same situation that our cover model is in, 
but if you do, we hope you have some 
protection. We're not going to tell you that 
a stun gun is your best protection, or that carrying a stun gun should 
make you feel confident in unsafe situations. But we think it's better 
to have some form of defense than none. The stun gun is a non-lethal 
weapon that can stop an attacker with its 75,000-volt discharge. 

The stun gun is not a toy. It is a dangerous project and it is not 
recommended for beginners. To find out how to build yours, turn to 
page 41. 



Next Month 



THE OCTOBER ISSUE IS 
ON SALE SEPTEMBER 2 



BUILD A SATELLITE-TV DESCRAMBLER 

To decode Telease-Maast programming. 

BUILD AN EPROM PROGRAMMER 

Choose the features you need most. 

SATELLITE JAMMING 

A look at its ominous potential. 



As a service to readers. RADIO-ELECTRONICS publishes available plans or information relating lo newsworthy products, 
Techniques and SGienlific and technological developments. Because of possible variances in the qualify and condition ol 
materials and workmanship used by readers, RADIO-ELECTRONICS disclaims any responsibility for the sale and proper 
functioning ot reader-buill projects based upon or Irom plans or information published in this magazine. 

Since some ol Ibe equipment and circuitry described in RADtQ-ELECTRQNICS may relate fo or be covered by U.S. patents. 
RADIO-ELECTRONICS disclaims any liability for the infringement of such patents by the making, using, or selling of any such 
equipment or circuitry, and suggests thai anyone Interested In such protects consult a patent attorney. 



Electronics 

Hugo Gernsback P884-T967) loundei 
M i larvej Gemsb* k 
cditor-inn hid emeritus 



Larry Stockier, F.HF, CET, editor-in-chiel 
and publisher 

EDITORIAL DEPARTMENT 
Art Kidman, editorial director 
Brian C. Fenlon, managing editor 
Carl Laron, VVB25I lv associate editor 
lelfrcy K. Hi ill /in. in. 
assistant technical editor 

Robert A. Young, assistant edttor 
Hill. in S. Martin, editorial associate 
Byron G. Wcls, editorial associate 
M. Harvey Gernsback, 

contributing editor 
lack Darr, CET, service editor 
Robert F. Scott, 

semiconductor editor 
Herb Friedman, 

communications editor 
Bob Cooper, Jr. satellite-TV editor 
Robert Gross hi, ill, circuits editor 
David Lachenbruch, 

< iiniribuling editor 
Richard D. Fitch, 

contributing editor 
Mark I. Rabillard, robotics editor 
Teri Scaduto Wilson, editorial assistanl 
Judith Kaplan, editorial assistant 

PRODUCTION DEPARTMENT 
Ruby M. Yee, production director 
Roberl A. W. Lowndes, 
editorial production 
Andre Du/.inl, technical illustrator 
Karen Tucker, advertising production 
Geoffrey S. Weil, product ion traffic 

CIRCULATION DEPARTMENT 
Jacqueline P. Cheoseboro, 

circulation director 
Wendy Alanko, 

cur liJ.ii inn analyst 

Theresa Inmbardo, 
circulation assistant 

( civer phnto by Roberl Lewis 

fv j ■■ i-.:i.i|i!n In Mates ( .rjphics 

Radio-Eleclronics, Gernsback Publica- 
linn',. Int., Executive Offices, 500-B Bi- 
Caunly Blvd., F.irmingdale, NY 11735, 
516.293-3000 

Radio-Electronics is indexed in 
Applied s< fence A Technology tndpx 
and Readers Guide to Periodical I itvr- 
ature. 

Microfilm <\ Microfiche editions are 
available. < on tact circulation depart- 
ment tor details. 

Advertising Sales Offices listed 
on page 114. 



ATI i 




NEW! 

Lower Price 

Scanners 

Communications Electronics^" 
the world's largest distributor of radio 
scanners, introduces new lower prices 
to celebrate our 15th anniversary. 

Regency? MX7000-GR 

List price S699.957CE price S469.95 

10- Band, 20 Channel • Crystalless • AC/DC 

Frequency range: 25-550 MHz. continuous co verage 
and 800 MHz. to 1.3 GHz. continuous coverage. 
The Regency MX7000 scanner lets you monitor 
Military, Space Satellites, Government, Railroad, 
Justice Department, State Department, Fish & 
Game, Immigration, Marine, Police and Fire Depart- 
ments, Broadcast Studio Transmitter Links, Aero- 
nautical AM band, Aero Navigation, Paramedics, 
Amateur Radio, plus thousands of other radio 
frequencies most scanners can't pick up. The 
Regency MX7000 is the perfect scanner to receive 
the exciting 1.2 GHz. amateur radio band. 

Regency® Z60-GR 

List price S299.95/CE price $179. 95/SPECIAL 
8-Band, SO Channel * No-crystal scanner 

Bands. 30-50, 58-103,118-138, 144-174, 440-51 2 MHz. 
The Regency Z60 covers all the public service 
bands plus aircraft and FM music for a total of 
eight bands, The Z6D also features an alarm 
clock and priority control as well as AC/DC 
operation. Order today. 

Regency® Z45-GR 

List price S259.95/CE price $159. 95/SPECIAL 
7- Band, 45 Channel • No-crystal scanner 

Bands: 30-50, 118-136, 144-174, 440-512 MHz. 
The Regency Z45 is very similar to the Z60 model 
listed above however it does not have the commer- 
cial FM broadcast band. The Z45. now at a 
special price from Communications Electronics. 

Regency® RH250B-GR 

List price S659.00/CE price $329. 95/SPECIAL 
10 Channel • 2S Watt Transceiver • Priority 

The Regency RH250B is a ten-channel VHF land 
mobile transceiver designed to cover any fre- 
quency between 150 to 162 MHz. Since this 
radio is synthesized, no expensive crystals are 
needed to store up to ten frequencies without 
battery backup. All radios come with CTCSS tone 
and scanning capabilities. A monitor and 
night/ day switch is also standard. This trans- 
ceiver even has a priority function. The RH250 
makes an ideal radio for any police or fire 
department volunteer because of its low cost 
and high performance. A60 Waff VHF 150-162 
MHz. version called the RH600B is available 
for $454.95. A UHF 1 5 waft version of this radio 
called the RU1 508 is alsoavailable and covers 
450-482 MHz. but the cost is $449.95. 

NEW! Bearcat® 50XL-GR NEW! Bearcat? 1 45XL-GR 



NEW1 Scanner Frequency Listings 

The new Fox scanner frequency directories wlf] help 
you find all the action your scanner can listen to. These 
new listings include police, fire, ambulances & rescue 
squads, local government, private police agencies, 
hospitals, emergency medical channels, news media, 
forestry radio service, railroads, weather stations, radio 
common carriers, AT&T mobile telephone, utility com- 
panies, general mobile radio service, marine radio 
service, taxi cab companies, tow truck companies, 
trucking companies, business repeaters, business radio 
{simplex) federal government, funeral directors, vet- 
erinarians, buses, aircraft, space satellites, amateur 
radio, broadcasters and more. Fox frequency listings 
feature call letter cross reference as well as alphabetical 
listing by licensee name, police codes and signals. All 
Fox directories are S14.95 each plus $3.00 shipping. 
State of Alaska-RL019"1 ; State of Arizona-RL025-1 ; 
Baltimore, MD/Washington, DC-RL024-1 ; Buffalo, NY/ 
Erie, PA-RL009-2; Chicago, IL-RL014-1; Cincinnati/ 
Dayton, OH-RL0O6-2; Cleveland, OH-RL017-1 ; Colum- 
bus, OH-RL003-2; Dallas/Ft. Worth, TX-RL013-1; 
Denver/ Colorado Springs. C0-HL027-1 ; Detroit, Ml/ 
Windsor, ON-RL008-3; Fort Wayne, IN/Lima, OH- 
RL001-1; Hawali/Guam-RL015-1; Houston, TX- 
RL023-1 ; Indianapolis, IN-RL022-1 ; Kansas City, MO/ 
KS-RU)11-2; Long Island, MY-RL02B-1; Los Angeles, 
CA-RL016-1; Louisville/Lexington. KY-RLO07-1; Mil- 
waukee, W I/ Waukegan, IL-RL021-1; Mlnneapolis/St. 
Paul. MN-RL010-2; Nevada/E Central CA-RL028-1: 
QWahomaCity/ Lawt on, OK- RL005-2 ; Orl an do/ Dayto na 
Beach, FL-RL01 2-1 ; Pittsburgh. PA/Wheeling. WV- 
RL029-1; Rochester/ Syracuse, NY-RL020-1; San 
Diego, CA-RLOI 8-1 ; Tampa/St. Petersburg, FL- 
RL004-2; Toledo, OH-RL0O2-3. New editions are being 
added rn on t h I y. For an area n ot s how n above c a 1 1 Fox at 
300-543-7892. In Ohio call 800-621-2513. 

NEW! Regency® HX1500-GR 

List price S369.95/CE price $239.95 
1 1-Band, SS Channel ■ Handheld/Portable 
Search * Lockout • Priority • Sank Select 
Sldallt liquid crystal display • EAROM Memory 
Direct Channel Access Feature • Scan delay 
Bands: 29-54, 1 18-138, 144-174, 406-420. 440-512 MHz. 

The new handheld Regency HX15D0 scanner is 
fully keyboard programmable for the ultimate in 
versatility. You can scan up to 55 channels at the 
same time including the AM aircraft band. The LCD 
display is even sidelit for night use. Includes belt 
clip, flexible antenna and earphone. Operates on 8 
1 .2 Volt rechargeable Ni-cad batteries (not included). 
Be sure to order batteries and battery charger from 
accessory list in this ad. 

Bearcat 5 100XL-GR 

List price $349,95/CE price $203. 95/SPECIAL 
9-Band, 10 Channel * Priority • Scan Delay 
Search • Limit • Hold • Lockout • AC/DC 

Frequency range: 30-50, 1 18-174, 406-5 12 MHz 
The world's first no-crystal handheld scanner now has 

a LCD channel display with backlight for low light use 
and aircraft band coverage at the same low price. Size is 
1 %" x 7Vs" x 2%!' The Bearcat 1 0OXL has wide frequency 
coverage that includes all public service bands (Low, 
High, UHF and"T' bands), the AM aircraft band, the 2- 
meter and 70 cm. amateur band3. plus military and 
f ed e rai govern m en t f re que nci es. Wow. ..whatascanner! 
Included In our low CE price is a sturdy carrying case. 
earphone, battery charger/ AC adapter, six AA ni-cad 
batte ries a nd f lexi ble an ten na. Ord er your scan n er n ow. 

Bearcat® 2 10XW-GR 

List price S339.95/CE price $209. 95/SPECIAL 
8-Band, 20 Channel • No-crystal scanner 
Automatic Weather • Search/Scan • AC/DC 

Frequency range: 30-50, 136-174,406-512 MHz. 
The new Bearcat 21 OXWisan advanced third generation 
scanner with great performance at a low CE price. 



List price S199.95/CE price $1 14.95/SPECIAL 
1 0-Band, 10 Channel • Handheld scanner 

Bands: 29.7-54, 136-174, 406-512 MHz. 
The Uniden Bearcat 50XL is an economical, 
hand-held scanner with 10 channels covering 
ten frequency bands. Itfeatures a keyboard lock 
switch to prevent accidental entry and more. 
Also order part* BP50 which isa rechargeable 
battery pack for $14.95, a plug-in wall charger, 
part # AD1 00 for$1 4.95, a carrying casepart # 
VC001 for $14.95 and also order optional 
cigarette lighter cable part # PS001 for$14.95. 



List price S179.95/CE price S102.95/SPECIAL 
10 Band, 1 6 channel • AC/DC * Instant Weather 

Frequency range: 29-54, 136-174, 420-572 MHz 
The Bearcat 1 45XL makes a great first scanner. Its low 
cost a nd h Ig h perform an ce 1 ets yo u hea r al! the act ion with 
the touch of a key. Order your scanner from CE today. 

TEST ANY SCANNER 

Test any scanner purchased from Communications 
Electronics' tor 31 days before you decide to keep It. If for 
any reason you are net completely satisfied, return It in 
original condition with all parts in 31 days, for a prompt 
refund (less shipping/ handling charges and rebate credits). 




Regency 
MX7000 




Regency 

HX1500 



NEW! Bearcat® 800XLT-GR 

List price S499.95/CE price $31 7.95 
12-Band, 40 Channel • No-crystal scanner 
Priority control • Search/Sean * AC/DC 

Bands: 29-54, 1 18-174, 406-512, 806-912 MHz, 
The Uniden 800XLT receives 40 channels in two banks. 
Scans 1 5 channels persecond. Size 9V*" xAW x 1 2Vx." 

OTHER RADIOS AND ACCESSORIES 

Panasonic RF-26O0-GB Shortwave receiver $179.95 

RD95-GR Uniden Remote mount Radar Detector. . . S1 28.95 

RD55-GR Uniden visor mount Radar Detector S98.95 

RD9-GR Uniden "Passport" size Radar Detector . . . S1 99.95 

BC-WA-GR Bearcat Weather Alert" S49.9S 

DX1 OOO-GH Bearcat shortwave receiver SALE. ., S348.85 
PC22-GR Uniden remote mount CB transceiver . . , S99.95 

PC55-GR Uniden mobile mount CB transceiver $59.95 

R1 060-GR flegsney 1 channel scanner SALE. , . , S3 2.95 

MX3000-GR Regency 30 channel scanner $229.95 

XL1 56-GR Regency 1 channel scanner $1 39-95 

UC1 02-GR Regency VHF 2 ch. 1 Watt transceiver . . . $1 24.96 
P1405-GR Regency 5 amp regulated power supply, . . 569,95 
P1 41 2- GR Regency 12 amp reg. power supply. ..SI 64.95 
MA2SS-GR Drop-in charger for HX1 200 i. HX1 500 . . . $64.95 

MAS1 B-GR Wall charger tor HX1 500 scanner $1 4.95 

MA51 B-GR Carrying case for HX1500 scanner, ., .$14.95 
MA257-G R Cigarette lightergordfor HX1 2/1 500 . . . $1 9.95 

MA91 7-GR Ni-Cad battery pack tor HX12Q0 $34.95 

SMMX7000-GR Svc man. tor MX7000 S MX5O00 . . . $1 9.9S 
SMHX30OO-GRServiceinan.fornegBncyMX3000 . ..$18.95 

B-4-GR 1.2 V AAA Ni-Cad batteries (set of four) $9.85 

B-a-GR 1 .2 V AA Ni-Cad batteries (set of eight) .... $1 7.95 

FB-E-GR Frequency Directory for Eastern U.S.A. $1 4.95 

F B-W-GR Freq u enoy Directory fo r Waste rn U.S. A~ ,, S 1 4.95 

ASD-GR Air Scan Directory $1 4.85 

SRF-GR Survival Radio Frequency Directory $14.95 

TSG-GR"Top Secret" Registry of U.S. Govt. Freq $14.95 

TIC-GR Techniques for Intercepting Comm. . .. $14.95 

RRF-Gfl Railroad frequency directory $14.95 

CtE-GR Covert Intelligence Elect. Eavesdropping ... $14.95 
A60tGR Magnet mount mobile scanner antenna, . . $35.95 

A7Q.GR. Base station scanner antenna $35.95 

US AM M- G R Mag mount V H F/U H F ant. w/ 1 2' cable. . . $39,95 
USAK-GR*" hole mount VHF/UHFant. w/ 17' cable ... $35,95 
USATLM-GR Trunk lip mount VHF/ UHF antenna. . . $35.95 
Add $3,00 shipping tor all accessories ordered at the same time. 
Add $1 2.00 shipping per shortwave receiver. 
Add $7.00 shipping per scanner and $3.00 per antenna 

BUY WITH CONFIDENCE 

To get the fastest delivery from CE of any scanner, 
send or phone your order directly to our Scanner 
Distribution Center!" Michigan residents please add 4% 
sales tax or supply your tax I.D, number. Written pur- 
chase orders are accepted from approved government 
agencies and most well rated firms at a 1 0% surcharge 
for net 10 billing. All sales are subject to availability, 
acceptance and verification. All sales on accessories 
are final. Prices, terms and specifications are suhjeot to 
ch a nge wit ho ut notice. Al I pri ces are i n U. S. dol lars. Ou t 
of slock itemswill be placed on backorder automatically 
unless CE is instructed differently. A $5.00 additional 
handling fee will be charged for all orders with a 
merchandise total under $50.00. Shipments are F.O.B. 
Ann Arbor, Michigan. No COD's. Most products that we 
sell have a manufacturer's warranty. Free copies of 
warranties on these products are available prior to 
purchase by writing to C E. Non- certifi ed ch ecks req u i re 
bank clearance. Mot responsible for typographical errors. 
Mail orders to: Communications Electron- 
ics!" Box 1045, Ann Arbor, Michigan 48106 
U.S.A. Add $7.00 per scanner for R.P.S./U.P.S. 
ground shipping and handling in the continental 
U.S.A For Canada, Puerto Rico, Hawaii, Alaska, 
or APO/FPO delivery, shipping charges are 
three times continental U.S. rates. If you have a 
Discover, Visa or MasterCard, you may call and 
place a credit card order. Order toll-free in the 
U.S. Dial800-USA-SCAN. In Canada, ordertoll- 
free by calling 800-221-3475. WUl Telex any- 
time, dial 671 -01 55. If you are outside the U.S. 
or in M ichigan dial 3 1 3-973-8888. Order today. 

Scanner Distribution Center™ and CE logos are trade- 
marks of Communications Electronics Inc. 
t Bearcat isa registered trademark of Uniden Corporation. 
t Regency Isa registered trademark of Regency Electronics 
Inc. AD #070ZS6-GR 

Copyrights 1986 Com muni cations Electron lea Inc. 

For credit card orders call 

1-800-USA-SCAN 

m 

TM "0 

m 

COMMUNICATIONS! 

m 

ELECTRONICS INC. = 

to 

Consumer Products Division § 

P.O.Box 1045 D Ann Arbor. Michigan 48106-1045 U.S.A. 
Call BOO-USA-SC AN orout»lde U.S. A, 31 3-973-8888 
CIRCLE 79 ON FREE INFORMATION CARD J 




WHAT'S N EWS 



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Three firms team up to 
manufacture custom IC's 

RCA and Sharp have signed a 
five-year agreement with Waf- 
erscale Inc., on manufacturing 
and technology of customer-spec- 
ified, highly-integrated semicon- 
ductor components. The bulk of 
the development will be in A 
pplication-Specific /integrated Or- 
cuits, or ASIC's. Those are circuits 
tailored to perform a customer- 
specified set of functions. 

A particularly promising ASIC 
design method, and the one on 
which the three companies will 
focus their joint efforts, is the "cell 
library" approach, in which a 
Computer-Aided Design (CAD) 
system modularly configures a 
custom circuit from pre-designed 
circuit function blocks called 
"cells." 

As part of the agreement, RCA/ 
Sharp Electronics has acquired 
about 7 percent of the stock of 
Waferscale and will be repre- 
sented on its board of directors. 

Voice forward systems to take 
over in offices? 

Voice store and forward (VSF) 
devices may change office pro- 
cedures in the next few years, by 
permitting sender and receiver of 
a telephone message to communi- 
cate asynchronously, suggests in- 
ternational market-research firm 
Frost & Sullivan. In VSF, the send- 
er's voice is digitized and stored on 
magnetic disk. When the receiver 
is ready to take the message, it is 
loaded into the machines's memo- 
ry, restored to analog form and 
played back at the listener's 
phone. 

Though one telephone answer- 
ing machine is cheaper than one 
VSF, the VSF machine can support 
a whole office, serving hundreds 
of users at an average cost that's 
much lower than that of individual 
tape answering machines. 



FCC proposes 1605-1 705-kHz 
guidelines 

The FCC recommends that the 
United States submit two pro- 
posals to the upcoming Interna- 
tional Telecommunications Union 
administrative radio conference in 
regard to the use of the expanded 
AM broadcast band (1605-1705 
kHz) in the western hemisphere. 
Those proposals are that allotment 
planning be used and that station 
power be limited to 10 kW. 

Allotment planning has several 
advantages over its alternative, as- 
signment planning. In assignment 
planning each signatory country 
must submit its complete and de- 
tailed requirements, pinpointing 
each prospective station and stat- 
ing power, antenna systems, and 
other characteristics for each. Un- 
der allotment planning, desig- 
nated frequencies are made avail- 
able for designated areas. Al- 
though the allotment of frequen- 
cies is based on the presumption 
of stations with presumed charac- 
teristics within presumed areas, 
the signatories are not bound to 
follow exact details. However, any 
departures from the plan must not 
increase interference to the ser- 
vices of other signatories. 

As to the proposed power limit, 
the Commission believes that 10 
kW provides for adequate service 
range, while making it possible to 
have enough stations to meet the 
requirements of the area. 

New polymer material simulates 
body tissue 

Scientists of the National Bu- 
reau of Standards report the 
development of a new material 
that acts like living body tissues 
when exposed to the electromag- 
netic waves produced by certain 
medical instruments. 

That substitute for living muscle 
marks a great step ahead for re- 
search by the Food and Drug Ad- 



ministration. The FDA will use the 
new material to evaluate the heat- 
ing patterns of devices used to 
generate the electromagnetic 
waves that heat body tissues for 
physical therapy, rewarm bodies 
after low-temperature surgery, 
and treat certain types of cancers. 
The new substance will provide 
the FDA with a more stable re- 
search material, having a longer 
shelf life than currently available 
polymers. The FDA also will place 
the new NBS "phantom flesh" in 
test kits for the National Cancer 
Institute and others to use in 
checking the quality assurance of 
their medical devices. 

Asian IV sets and tubes are 
"dumped" on U.S. market 

Jerry Pearlman, Zenith chair- 
man and president, speaking at 
the annual shareholders meeting, 
condemned the "unfair and 
largely illegal" trade practices of 
Japanese, Korean, Taiwanese, and 
other Far-Eastern manufacturers of 
television sets. 

Japanese TV manufacturers have 
been operating under a U.S. 
dumping finding since 1971. In 
1984, Korean and Taiwanese man- 
ufacturers were also found guilty 
of dumping. To avoid dumping 
penalties, Far-Eastern producers 
have been shifting their exports 
from fully assembled TV sets to 
kits, including picture tubes and 
electronics. Those kits can be sim- 
ply "snapped together" at the ex- 
porter's U.S. warehouses. Picture 
tubes are also being dumped di- 
rectly at less than their fair-market 
price, Mr. Pearlman said. 

Zenith asks that the government 
investigate those cases and take 
action against Far-Eastern man- 
ufacturers. The company is en- 
couraged by bills seeking to stop 
unfair import practices; those bills 
have been initiated in both the 
House and Senate. R-E 



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Video 

News 




DAVID LAGHENBRUCH 

CONTRIBUTING EDITOR 



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• Universal remote control. Recently, one of 
the big features in many home -entertainment 
lines has been the unified remote-control, a unit 
that is capable of operating both a TV and a 
VCR — assuming both are made by the same 
manufacturer. The rub is that most people own 
TV sets and VCR's made by different 
manufacturers. GE introduced one solution last 
year when it marketed its programmable remote. 
That unit lets yon operate several different pieces 
of equipment using just a single remote control; 
the GE remote "learns" the code used by your 
different infra-red remote control systems in just 
a few simple steps. 

How north American Philips has introduced a 
'nniversal remote" as standard equipment with 
most remote-control TV sets in its Magnavox, 
Sylvania, and Philco lines. That remote is pre- 
programmed with infrared codes for 29 different 
brands of VCR's (in addition to the brand of TV 
set with which it is sold). The user merely aims 
the remote at his VCR, simultaneously presses 
two buttons, and the remote-control unit starts to 
sequence through all of its built-in program 
codes. When it finds the right one and the VCR 
starts to change channels, the user merely 
releases the two buttons, and from then on the 
remote will control the VCR as well as the TV set. 
A more deluxe unit is also pre-programmed to 
operate with 15 different brands of remote- 
control cable-TV converters. 



• And Philips makes four. Speaking of Worth 
American Philips, the illustrious worldwide 
Philips brandname will soon appear on some 
consumer electronics products in the U.S. 
Beginning in 1987, the company will affix that 
name to a new line of audiophile and videophile 
products, giving the company a fourth trade- 
name here and finally giving the Philips name 
visibility in the U.S. (Faithful audio fans will 
recall the Philips name was used on turntables 
and loudspeakers here several years ago.) In the 
early days of radio, the Philips name was kept out 
of this country because of the possibility that it 



would infringe on the name Philco. Now North 
American Philips owns the Philco trade name. 

• Big, bigger, biggest. That sequence, applied 
to color picture tubes, might refer to 27, 35, and 
40 inches. The 35-inch tube was recently 
introduced by Mitsubishi and is featured in a 
$3,300 color set. So encouraged has Mitsubishi 
become with the idea of large direct- view picture 
tubes that it plans to introduce a 40-inch color 
monitor-receiver priced at $9,000 to $12,000 to- 
Jap an. 

Although the big tube is new, the idea isn't. In 
the 1950's, the late TV-pioneer Dr. Allen B. 
DuMont proposed theater- sized direct- view 
monochrome tubes with diagonal measures 
approaching 10 or 11 feet. 

• Flat is flat. There has been a lot of 
discussion in the last couple of years about "flat 
faced" picture tubes. Toshiba's former Flat Square 
Tube was recently renamed Flattest Square Tube. 
How it will have to be renamed something else, 
because Zenith has introduced a color picture 
tube whose face is flat, period. So flat, in fact, that 
a sheet of window glass can be used for implosion 
protection. The secret of Zenith's new FTM tube is 
a Flat Tension Mask, which gives the tube its 
name. Instead of the normal domed shadow 
mask, the new tube has a thin foil shadow mask 
stretched flat, held under tension and sealed into 
the glass just behind the faceplate. Unlike 
conventional shadow masks which can expand 
and shift with heat, Zenith says the stretched 
mask doesn't move at all under most conditions, 
even at brightness that can cause distortion or 
wrong colors in conventional tubes. 

Also, because the face is flat, it inherently is 
less reflective. Thus an image on the tube appears 
similar to a slide viewed on a screen or in a 
viewer. The first FTM tube, available by the 
middle of 1987, will be a 14-inch ultra-high- 
resolution computer display, but future versions 
are expected for TV and all other CRT 
applications. Zenith says its cost involves a 'very 
modest" premium over conventional tubes. H.-E 



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Only NRI gives you a 27" high-resolution 

stereo color TV you build to prepare you for 

today's video servicing careers. 




Become one of America's most sought-after technicians . . . 

put your talents and spare time to work for you in the 
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Train in state-of-the-art video/audio 
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pace that suits you best. 



There's no stopping the incredible 
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ucts, entirely new technologies have 
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trained technician as never before. 

Now at S26 billion in annual sales, 
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sales alone are expected to hit 16.2 
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And the revolution lias spread to the 
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for employee training, data storage, 
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The Video Revolution 
Is Just Starting 

Already, disc players can handle audio 
CDs and laser video discs. And now 
there are machines that will accom- 
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Camcorders are becoming smaller, 
lighter, and more versatile ... 8 mm 
video equipment produces high- 
resolution pictures and digital audio. 
By 1990 our TVs will become inter- 
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Can you see the opportunity? The serv- 
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Even if you've never had elec- 
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Hands-On Training As You Build 

a 27" Stereo TV 

In just hours you assemble an excep- 
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**/ tCTIDH AUDIO 



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NRI has purposely designed your 
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This new state-of-the-art Heath/Zenith 
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Step Into the Future Today 

The richest reward you gain 
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Send For Free Catalog 

Now is the time to act. Send the post- 
paid card to us today. You'll receive 
our 100-page catalog free. It's filled 
with all the facts you'll want to know 
about our training methods witit full 
details on the equipment you'll use 
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us the leading technical school today. 
(If someone has already used the card, 
write to us at the address below.) 



NKI's commitment to you goes beyond 
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School of Electronics 

McGraw-Hill Continuing 

Education Center 
3939 Wisconsin Avenue, NW fiJ 
Washington, DC 20016 Kfili 



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WRITE TO: 

ASK RE 

Radio-Electronics 
500-B Bi-County Blvd. 
Farmingdaie, NY 11735 



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FIG.1 



TRIMMING AM AUTO RADIO 
Recently, I replaced the AM radio in 
my car with an AM/FM stereo model 
and installed a new antenna de- 
signed for AM/FM operation. FM 
performance is fine, but AM recep- 
tion is miserable and doesn't com- 
pare with that of the set it replaced. 
Sensitivity is low, selectivity is poor, 
and there is a great deal of cross-talk 
from co-channel and adjacent-chan- 
nel stations. What's wrong? Is there a 
defect in the AM section of the radio, 
or is the trouble in the installation?-- 
R. U. P., Long Beach, CA 

Figure 1-a shows a typical auto- 
motive AM antenna input circuit. 
A small padder capacitor, Cp, is 
connected across the coil, which is 
permeability tuned. That capaci- 
tor, along with stray circuit capaci- 
tance, ensures high selectivity. 

The highest frequency is tuned 
when the slug (the powdered-iron 
or ferrite core) is out of the coil; 
tuned frequency decreases as the 
core moves into the coil. The in- 
ductance of the coil is chosen so 
that the coil can be tuned to the 
highest frequency (1550 or 1600 
kHz) by adjusting a trimmer. 

The antenna is connected to a 
tap on the high (i. e., high-imped- 



ance) end of the antenna coil 
through a shielded cable and a 
DC-blocking capacitor, C a . A trim- 
mer capacitor, C T , is connected 
between the tap and ground. 

Figure 1-b shows how various 
stray capacitances must be consid- 
ered part of the circuit. Capacitor 
C A represents the capacitance be- 
tween the antenna and the body of 
the car, and C c is the capacitance 
of the shielded connecting cable. 
Blocking capacitor C B is not shown 
because it is effectively in series 
with C, and, because it is much 
larger than C A and C c , can be ig- 
nored. Note that C A and C c - affect 
the resonant frequency of the cir- 
cuit; their effect is most pro- 
nounced at high frequencies. 

When a newantenna is installed 
(or the radio is replaced), trimmer 
C T must be adjusted. Use a service 
manual, the manufacturer's in- 
structions, or, lacking those, fol- 
low this procedure: 

1. Extend the antenna to full 
length. 

2. Tune in a weak station be- 
tween 1200 and 1500 kHz. 

3. Adjust the volume control for 
maximum output, 

4. Locate C T . You can usually ad- 
just it through a hole in the case 



near the antenna's input jack. 

5. Use a non-conductive align- 
ment tool and adjust the trimmer 
for maximum output, as heard 
through the speaker. If you can't 
tune in a signal at the high-fre- 
quency end of the band, adjust the 
trimmer for maximum back- 
ground noise. Now, assuming 
your radio has no other problems, 
reception should be drastically im- 
proved. 

Here's a cheap-and-dirty trick 
you can use to check alignment. 
Tune in a weak high-end station 
and turn up the volume. While 
standing on dry ground, grasp the 
antenna near the tip. If the volume 
drops, alignment of the antenna- 
circuit is probably OK. The reason 
is that you are detuning the circuit 
by adding capacitance between 
the antenna and the car body. 

FLUORESCENT LIGHTS 
How does a fluorescent lamp work? 
I know that it usually needs a ballast 
and a starter, but I can't find any 
information on its principles of oper- 
ation. — D. A. 

A good article on the subject ap- 
peared in the March 1976 issue of 
Popular Mechanics. The article is 
called "What You Should Know 
About Fluorescent Lamps;" it ap- 
pears beginning on page 120 of 
that issue. Your local library may 
have that issue on file, or it may be 
able to borrow a copy for you from 
another library. 

Another good source of infor- 
mation is the booklet Fluorescent 
Lamps {TP-111R, Dec. 1978), pub- 
lished by General Electric Compa- 
ny, Lamp Products Division. You 
may be able to get a copy of that 
booklet from General Electric, 
Lighting Business Group, Nela 
Park, Cleveland, OH 44112. R-E 



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Letters 



, 1Z l IFl'i 



SPEED-GUN CALIBRATOR 

The address of the parts supplier for 
the speed-gun calibrator was listed in- 
correctly in the Parts List ("Build This 
Radar Speed-Gun Calibrator," Radio- 
Electronics, August 1986). The cor- 
rect address is: Microwave Control, 
1701 Broadway, Suite 263, Vancouver 
WA 98663. Microwave Control can be 
reached by telephone at 1-206-693- 
6843. 



LARGE TESLA COILS 

First, I would like to say that I 
enjoy Radio-Electronics. It has 
something for everybody, and 
your articles are both informative 




and interesting. I especially like 
Jack Darr's "Service Clinic" and the 
"Antique Radios" department. 

Now I have a couple of ques- 
tions. I am interested in large Tesla 



Card Size Digital Multimeter 




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LETTERS 

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soo-B a/-coo/vrr &ot/L£ vard 

FAKMMGOALE, NY //7S5 



coils — the RF oscillator type, not 
especially the spark gap. Could 
you feature an article on that sub- 
ject, or could you tell me a source 
of article reprints or construction 
plans in that area? 

Also, I think that other readers 
also might like to see schematics 
of antique radios presented in the 
"Antique Radio" department. That 
should help us to restore old sets. 
NOLAN F. SMITH 
Fayetteville, NC 

THE REGENCY MX-7000 

I have been the proud owner of 
a Regency MX-7000 for quite some 
time now, and want to expand on 
the review it received in the May 
1986 Radio-Electronics. There are 
several points that require correc- 
tion and also a very important as- 
pect of that unit that was not 
mentioned. 

The MX-7000 was somewhat un- 
derestimated by your review, even 
though what was described would 
be enough to put it at the top of 
the list. For instance, the top-end 
frequency coverage is specified to 
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12.5, or 25 kHz steps, depending 
on the service of primary interest. 
As for variable bandwidth, the unit 
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Of some interest is the ability to 
listen to broadcast FM transmis- 
sions between 88 and 108 MHz. I 
have a feeling that, for some pro- 
spective buyers, that single fact 
may be enough to allow some 
strain on the budget. Needless to 
say, the MX-7000 is quite a radio 
and is worthy of consideration by 
the serious user. 

A couple of quick points: The 
article noted that the BNC con- 
nector on the back of the MX-7000 
is more secure than the con- 
nectors normally found on 
monitor radios. That's true, but 
there's an even more significant 
reason for its use. The Motorola- 
type connectors (and, for that mat- 
ter, the so-called UHF connectors) 
become inadequate at higher fre- 
quencies. A BNC connector is 
what is called a "constant imped- 
ance" connector. That means that 
it exhibits the same electrical 
properties as the transmission 
line, and results in a more efficient 
signal transfer. I can vouch for that 
through experience with the 450- 
MHz ham band, where using a 
UHF-type barrel connector be- 
tween two cables will do serious 
damage to your SWR. When oper- 
ating at near microwave frequen- 
cies (0.8 to 1.3 GHz) the effect 
would be very substantial. 

Second point: In looking at the 
frequencies that are stored in the 
20 memory channels, it appears 
that they are more likely for testing 
and adjustment of the unit. Trying 
to assume which frequencies — of 
over 200,000 possibilities — are 
going to be popular may be a bit 
presumptuous. 

I regret to say that one quality of 
the MX-7000 is not so admirable: 
the sluggish way in which it gets 
around to doing things. No doubt 
the microprocessor (mounted on 
the back of the front panel) is very 
busy, but the speed at which it op- 
erates is responsible for the lack of 
crisp response that one should get 
from the keypad and for the some- 
what lethargic scanning speed. 
Fortunately, the manufacturer de- 
cided not to use a crystal-based 
clock, and that gives the user an 
opportunity to find out just how 
fast this thing really can go. The 
resistor marked R6 on the back of 
the front-panel assembly is part of 
an R/C time-constant circuit which 



sets the processor's clock speed; 
its value can be changed easily. I 
found a value of 39K suitable for 
my unit. 

Unfortunately, it has been a 
while since I changed that part, 
and I'm not sure of its original val- 
ue — but there is a substantial in- 
crease in speed. To make installa- 
tion of the new resistor easier, I 
didn't bother to desolder the leads 
of the old resistor; I simply clipped 
off the old one near the board and 
tacked the new one on. 

The performance increase using 
the new value effectively elimi- 
nates the MX-7000's single limita- 
tion. Most likely, the manufacturer 
was trying to be conservative in 
selecting the processor speed to 
ensure reliable operation 
throughout the temperature spec- 
ification. In reality, most users 
would not subject it to such ex- 
tremes, and in any case would be 
unable to vary the value of R6 
should erratic operation occur. As 
for my unit, it has been in our van 
through all sorts of environmental 
conditions and hasn't burped 
once. 

Final note: While the price may 
seem a bit high, there are outlets 
who sell the MX-7000 at a very 
competitive price. As an example 
one of your advertisers sells that 
unit for under $400.00. At that 
price, considering the advanced 
functionality, and with the change 
in clock speed, the Regency 
MX-7000 graduates with high hon- 
ors. 

CHARLES P. SCOTT 
Mt. Sterling, KY 

VOLTAGE COMPARATORS 

I have just read the article on the 
care and feeding of voltage com- 
parators in the June, 1986 Radio- 
Electronics, and am impressed 
with the range of circuits and ap- 
plications available. However, I 
find one of the circuits a bit less 
than impressive, due to two rather 
well-hidden flaws that will prevent 
its being useful for its intended 
purpose. 

Thecircuit in question is the one 
shown in Fig. 16. That circuit is in- 
tended to be a "micro-power" cir- 
cuit by virtue of applying power to 
the sensing and control circuit for 
a very small fraction of the time. 
The first problem with that ap- 



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proach is that the sample-pulse 
generator, which determines how 
long the main control-circuit is 
powered, must itself be powered 
continuously in order to work. 
That flaw, perhaps, is not so bad, 
since presumably the sample- 
pulse generator could be built out 
of CMOS components and draw 
minimal power. 

A much worse difficulty arises 
from the fact that, when the con- 
troller determines that power 
must be applied to the load, the 
relay will draw considerable 
power, regardless of how low the 
drain of the control circuit is. 
Thus, the overall circuit is truly mi- 
cro powered only if the load is nev- 
er turned on! But in that case, who 
needs a control circuit? 
HOWARD MARK 
Suffern, NY 

OOOOPS! 

Several errors crept into the arti- 
cle, "Build This Little Leakage 
Checker," which appeared in the 
May 1986 issue. In the Parts List on 
page 56 and the schematic on page 



57, C3 should be 0.0022 iiF, poly- 
ester. Resistor R22 in the schematic 
should be 249K; it is shown cor- 
rectly in the Parts List. Switch S1-b 
is shown incorrectly in the sche- 
matic; it should complete the dis- 
charge path to ground as shown in 
the block diagram on page 56. 

In the parts-placement diagram 
on page 58, capacitor C7, which is 
located between Q1 and R5, 
should be C2 (0.1 tiF). Near IC3, 
R15 should be R4 (270 ohms). And 
the locations of D11 and R14 are 
transposed, as are the locations of 
D12 and R13. 
GARY McCLELLAN 

BI-POLAR POWER SUPPLY 

Regarding the bi-polar power 
supply shown on page 9 of the May 
1986 Radio-Electronics, I hope that 
N. J. S. did not build the supply 
and try to use it for his project. Two 
errors make the project unworka- 
ble. The center tap of T1 should go 
(only) to the junction of C1 and C2; 
that point is circuit ground. In ad- 
dition, the junction of D1 and D2 
should go (only) to the negative 



side of C2. That is the negative 
nine-volt output of the circuit. 

Rather than using individual 
1N4001 diodes, a fullwave bridge 
rectifier, such as Radio-Shack cata- 
log number 276-1151, could be 
used. It costs only pennies more, 
is rated 50PIV, 1.5 amps, and is 
small. The whole unit is built into 
one of Radio-Shack's plastic en- 
closures. The size of the case de- 
pends on the size of the 
transformer used. Output termi- 
nals are used for easy connection. 
It makes a nice, neat package 
when used in conjunction with 35- 
volt radial-type capacitors. 

I hope that N. J. S. can use the 
corrected circuit to full advantage 
now. 

WILLIAM N. BROOKS 
Henrietta, NY 

KIRLIAN PHOTOGRAPHS 

The article, "How to Make 
Kirlian Photographs," which ap- 
peared in the May 1986 Radio-Elec- 
tronics, has done a disservice to 
your readership and to science by 
continued on page 87 



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RAG ELECTRONICS, INC. / 21 41 8 Parthenia Street/ Canoga Park, CA91 304/1-81 8-998-6500 



Equipment Reports 



Soar Model 3430 DMM 



A 4V2-digit meter with ail 
the beils and whistles 



CIRCLE 9 ON FREE INFORMATION CARD 







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FOR MOST OF US, SELECTING A DMM 

boils down to a process of weigh- 
ing which features we need or 
want against the price of the in- 
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doing without some of the fea- 
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'Batteries not included. 



CIRCLE 134 FOH DEMO, CIRCLE 203 FOR LITERATURE 



24 



npson Electric Co. I M^ M J ■ MJ| tf 

Introduces M - I . I . 

77ie Ultimate in Low-Cost Test Equipment 

At last! Here is your opportunity to take your pick from a new test equipment line that has all 
the features you need and more and at a price that is unbelievably low. 



MODEL 9340 
Pocket size, 3'/2-digit 
DMM with 20 megohm 
range and 10 megohm 
input resistance 

144" 



MODEL 9670 

Digital capacitance 
tester covering 0.1 pF 
to 20,000 (iF 



MODEL 9101 

Compact V0M with 27 
ranges, including a 
100 megohm range 



iiT*** 



MODEL 9301 

3 'h -digit, hand -held 
DMM with 0.25% 
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sggoo 






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MODEL 9120 

Analog V0M with 12 A 
DC range and output 
jack 






MODEL 9401 

4 'A -digit, full function, 
hand-held DMM with 
.05% accuracy and 
data hold 
s 12 goo 



MODEL 9701 

digi-clamp™ compact 
AC clamp-on volt-ohm- 
ammeter with data hold 
s 69°° 



]?< 



mercer 

ELECTRONICS 

Division of Simpson Electric Company 

859 Dundee Avenue, Elgin, IL 60120-3090 
(312) 697-2265 • Telex 72-2416 



MODEL 9370 

3 Vi -digit autoranging 
DMM with a memory 
mode and 0,5% basic 
DC accuracy 

s 59 m 



Mercer Electronics products reflect the design and quality 
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in Stock. . .Available Now! Stop in at your nearest distributor 
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bleshooting sophisticated elec- 
tronics gear. The Soar (1126 Cornell 
Ave., Cherry Hill, NJ 08002) model 
3430 is a DMM designed with 
those users in mind. As a bonus, 
considering its features, the unit is 
a bargain; just a few years ago, it 
would easily have cost many times 
more. 

The model 34 30 

The model 3430 is a micro- 
processor-controlled, true rms- 
reading, 4!A-digit DMM. It features 
13 functions, and either auto or 
manual ranging modes can be se- 
lected at the press of a button. 

Unlike conventional DMM's that 
are 20,000-count units, the 3430 is 
a 25,000-count instrument. That al- 
lows for full 4 1 />-digit resolution to 
the second decimal place. For ex- 
ample, 0.1-volt resolutions are 
possible on the1000-volt DC range 
and 1-kilohm resolutions are pos- 
sible on the 25-megohm range. At 
the other end of the scale, quan- 
tities as lowas10u,Vand0.01-ohms 
can be read. 

Turning first to the standard 



functions, the meter can measure 
AC and DC voltages over 5 ranges 
from 250-mV to 1000-volts (750- 
volts AC) full-scale. Accuracies on 
the DC ranges are specified as 
0.05% ±2 digits or better. On the 
AC ranges accuracy is 0.5% ±2 dig- 



Soar 3430 




OVERALL I Mill 
PRICE ■ 










EASE\_ 










of use m 


INSTRUCTION F 
MANUAL |_ 










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| 1 | 2 [ 3 [ 4 | S 6 | 7 | 8 | 9 ] 10 


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its on all ranges except 750 volts, 
where it is 1% ± 2 digits. 

Resistance is measured over 6 
ranges from 250 ohms to 25 
megohms full-scale. Accuracies 
are specified as 0.06% ±2 digi- 
ts ±0.02 ohms on the 250-ohm 
range; 0.06% ±2 digits on the 
2500- , 25,000-, and 250,000-ohm 




Weller® 
WTCPR $77.50 

Safe for IC soldering. Closed loop, low-voltage circuit 
automatically controls output. 700 F 1/16" screwdriver tip 
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non-heat sinking iron holder, storage tray for extra tips 
and tip cleaning sponge with receptical. Send for free 
W.S. Jenks & Son electronics tool catalog for complete 
accessories. 





FREE CATALOG! 

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CIRCLE 66 ON FREE INFORMATION CARD 



ranges; 0.5% ± 2 digits on the 2500 
kilohm range, and 2% ±3 digits on 
the 25-megohm range. 

The unit measures AC and DC 
current over two ranges, 250-mA 
and 10-amps full-scale. Accuracies 
are 0.25% ±2 digits (250-mA DC), 
1%±2 digits (10-amps DC}, 
0.75% ±10 digits (250-mA AC), and 
2% ±10 digits (10-amps AC). 

All ranges and functions, except 
the 10-amp range, are overload 
protected. 

Special functions 

The 3430 also has a host of spe- 
cial functions. Those so-called 
bells-and-whistles quickly be- 
come indispensable when you've 
become accustomed to using 
them. Note that while many other 
meters have some of these func- 
tions, few have integrated as many 
as the 3430 in one unit. 

CONTINUITY CHECK and DIODE TEST 

functions have now become com- 
monplace. Thay even can be 
found on some low-end instru- 
ments. Both functions are, of 
course, present here. They work 
as you would expect, and the 
continuity-test function has the 
requisite audible indicator. 

More interesting are the peak 
hold and data hold functions. 
Those will freeze either a high 
reading or a current reading on the 
display. The peak-hold function 
will work only when the meteris in 
the manual mode and only for AC 
and DC voltage, AC and DC cur- 
rent, and temperature (more on 
that in a moment). Further, it will 
capture any transitory reading that 
has a duration of greater than 5 ms. 

Since we've already alluded to 
it, let's next turn to the temperature 
function. The meter, through a 
standard k-type thermocouple 
(not included, but available as an 
accessory), can measure tem- 
perature and display the result in 
either °C or °F. The measuring 
range is - 50°C to 1200°C or -58°F 
to 2192°F. Accuracies are 0.5% ±3 
digits (°C) and 0.5% ±5 digits (°F). 

Relative voltages can be dis- 
played using the dbm function. In 
that function, all readings are ref- 
erenced to dBm (0.7746-volts rms 
at 600 ohms, 1 mW). 

A rei. or relative function relates 
all subsequent measurements to 
an input reference. That function 



COMB 



Authorized Liquidator 



NOTE: Monitor not 
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$ 837.00 

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Liquidation Price , 

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TO ORDER 
INDIVIDUAL COMPONENTS: 
PLUS/4'" COMPUTER 
Mfr. List $ 299.00 



Additional Features of 
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Data base of 999 records. Com- 
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Item H-1 . 1.12-5035-001 Ship, handling: S3.00 

DISK DRIVE 

Mfr. Orig. Li st s 269.00 



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Item H-1 442-3553-013 Ship, handling: $8.00 



$149 



Credit card customers can order by phone, 
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7 days a week. VISA' 

Toll-Free: 1-800-328-0609 

Sales outside the 48 contiguous states are subject Io 
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SEND TO: Item H-144Z 

C.O.M.B. Direct Marketing Corp. 

1405 N. Xenium Lane/ Minneapolis, MN 55441-4494 

Send the following items. (Minnesota residents add 6% 
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Send COMPLETE 5YSTEM{s) Commodore Plus/4 T ". 

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Send COMMODORE PLU5/4 r " COMPLITER(s) Item H- 

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Send DISK DHIVEJs) item H-1 442-3553-013 at $149 

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□ My check or money order is enclosed, (Ho delays in 

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Charge: □ VISAW □ MasterCard « D American Express" 

AccL No. Exp. L 

PLEASE PRINT CLEARLY 

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27 



can only be selected when the 
meter is in the manual mode and 
will work on AC and DC current 
and voltage ranges as well as on 
the resistance range. 

One disadvantage of a 414-digit 
meter such as this one is that it 
takes a relatively long time to ob- 
tain a reading. Maximum response 
times can range from one to as 
many as eight seconds. For in- 
stances where speed is more im- 
portant than a high degree of 



accuracy, the meter can be placed 
in a 3'/2-digit mode. In that mode, 
the least significant display digit is 
blanked and response times are 
significantly shortened. 

Last, but certainly not least, the 
3430 features a frequency mode. 
In that mode, the meter acts as a 
100-kHz (actually, a 99.999-kHz) 
frequency counter. Accuracy is 
specified as 0.05% of reading and 
resolutions as high as 0,001 Hz are 
possible. 



VCR 

REPAIR MADE EASY 

Sams is your source for reliable, state-of-the-art 
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The Saras PHOTQFACT* standard notation format, your tool (or 40 
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■ VCR manuals are approximately SO pages, I'A x 1 1 , and loose-leal 
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Sams VCR Technical Service Data is available for J 2 1. 95 each from 
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Or Call S(HM28-SAMS 
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Operator sss 



Odds and ends 

The large LCD readout is capa- 
ble of displaying a full range of 
annunciators. In addition to show- 
ing range, function, etc., such 
conditions as overvoltage and low 
battery are clearly indicated when 
appropriate. The input connectors 
are of the recessed safety type. 

All functions and modes are se- 
lected using a front-panel keypad. 
Operation in both auto and 
manual modes is simple and 
straightforward. 

Battery life is estimated to be 100 
hours with alkaline units. An op- 
tional AC adapter is available also. 

The instruction manual is 
nothing special. To make things 
worse, because of a poor transla- 
tion job (both the manual, and the 
meter were produced in Japan) it 
takes quite a bit of effort to get the 
most out of the manual and hence 
the meter. 

But don't let that stand between 
you and this outstanding instru- 
ment. At $339.00, the model 3430 is 
the answer to many a technician's 
wish list. R-E 

continued on page 32 



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Learn about surface-mount 

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aware that Surface A-fount Techn- 
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cram more circuitry into a given 
space. It's important for anyone 
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hands-on experience with surface- 
mount devices. We recently exam- 
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The SMT Training Kit contains an 
assortment of surface-mount de- 
vices, prototyping boards, inter- 
connection materials, and a train- 
ing manual. The devices supplied 
with the kit include almost three 
hundred chip capacitors, three 
hundred Ys-watt, thick-film re- 
sistors, ten 1N914 diodes in SOT-23 
packages, and ten 2N2222 tran- 
sistors, also in SOT-23 packages. 

Although there are no surface- 
mount IC's supplied with the kit, 
the double-sided epoxy-glass pro- 
totyping PC boards have tinned 
foil patterns to accommodate 
SOIC (Small Outline /ntegrated 



Circuit) and PLCC (Plastic Leaded 
Chip Carrier) IC's. Of course the 
kit also includes solder, solder 
paste, terminal pins, stainless 
steel and plastic tweezers, and 
conductive adhesive. 

The most important part of the 
SMT Training Kit, however, is the 
training manual. For the most part, 
it is very well written. It begins 



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use it most effectively. A SMT re- 
source directory is included in the 
manual. It contains a listing of 
manufacturers and suppliers of 
SMT products. 

Getting some experience 

Let's look at an example of how 
the kit can give some practical 
hands-on experience. (We will as- 
sume that you have the IC's that 
you'll need to complete your cir- 
cuit.) The first step is to plan the 
board layout by drawing it on the 
layout paper that's provided. Once 
that's done, you're ready to mount 
components. If you've never 
worked with surface mount de- 
vices, it can be a real learning ex- 
perience. For example, since 
surface-mount components don't 
have mounting holes to hold them 
in place, there's no easy way to get 
them to stay in place while you 
solder them. Tack soldering 
works — once you get the hang of 
working with chip components — 
but it's not the easiest way. That's 
especially true if you're working 
with IC's with "J" leads, which 
bend in under the package. There 
are two compounds — solder paste 
and conductive adhesive — that let 
you get you components mounted 
in place reliably. 

Solder paste is a mixture of tin/ 
lead solder and flux, and there are 
two common ways to use it. The 
first is to apply the paste to the 
solder pads using a syringe. The 
other is simply to dip the compo- 
nent contacts into the paste. Once 
your components are "pasted" on 
the board, the real soldering be- 
gins — but not with a soldering 
iron! 

Solder reflow is the method 
used to melt the solder paste. 
First, the entire board is pre-heat- 
ed in a convection oven (85°C for 
about 20 minutes) to drive off un- 
desirable volatile solvents, to 
lessen thermal shock to the board 
and its components, and to get 
better solder contacts. After pre- 
heating, the oven temperature is 
increased to about 210°C to melt 
the solder. Solder reflow should 
occur within about 30 seconds. 
You have to be careful and quick — 
electronic components cannot 
withstand the temperature of mol- 
ten solder for very long. (If a con- 
continued on page 38 



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The deck shares a 181-channel 
cable-compatible tuner/timer with 
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air automatically. Nineteen stcp- 
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as "Timer has not been set," and 
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The TV set itself is a 27-inch 
screen model and features a digital 
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PIP allows users to watch one 
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The model KV-25VXR has a sug- 
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STEREO HEADPHONES, the model 
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A soft, semi-elastic pad on each 
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The model ATH-M7 PRO is 



priced at $99.95.— Audio-Technica 
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DC POWER SUPPLY, the model 
1630, features regulated voltage 




CIRCLE 33 ON FREE INFORMATION CARD 

and current outputs that can sup- 
ply a maximum of 30 volts and 3 
amps respectively. In addition, the 
model 1630, has buiit-in metering; 
two current ranges; a pre-reg- 
ulator to limit internal dissipation; 
isolated outputs so that either po- 



larity may be floated or grounded; 
and reverse-polarity protection to 
prevent damage to the power sup- 
ply from an external voltage or a 
reversed polarity input. 

It also has fully-adjustable cur- 
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maximum output current) that 
protects the circuit under test and 
the power supply. The model 1630 
can be hooked up in series or in 
parallel with another model 1630 
for 0-30-volt, 6-amp, or 0-60-volt, 
3-amp operation. 

The model 1630 comes with test 
leads, spare fuse, schematic and 
parts list, and complete instruc- 
tion manual. It is priced at 
$225.00.— B&K Precision, Dynascan 
Corporation, 6460 West cortland 
Street, Chicago, IL 60635. 

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model YM-950, is a 25-inch color 
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input and output jacks, some of 
which, along with the con- 
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panel. Connections to and from an 
audio system, a VCR, a videodisc 
player, a game, and a computer 
can be made easily and quickly. 

The model YM-950 has a sug- 
gested retail price of $950.00. — 
Yamaha Electronics Corp., USA, 
6660 Orangethorpe Avenue, 
Buena Park, CA 90620. 

SCANNER BEAM ANTENNA 
provides 30-50 MHz low band, 
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mobile reception. Hams can use it 
for transmitting up to 25 watts on 
the144-, 220-, and 420-MHz bands. 
The Scanner Beam can also be 
used with an inexpensive TV an- 
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A baiun transformer, offset pipe, 
and all mounting hardware are in- 
cluded. (A type F connector on the 
user's coax is required.) The ap- 
proximate size of the Scanner 
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EQUIPMENT REPORTS 



continued from page 33 



vection oven is not available, a hot 
plate can be used.) After you re- 
move the board from the oven and 
let it cool, you must remove the 
solder flux and carefully inspect all 
solder bonds. 

Conductive adhesive, as its 
name implies, is a compound that 
lets you simply "glue" compo- 
nents to the board. Unfortunately, 
the adhesive was not included 
with our pre-production version of 
the SMT Training Kit. The com- 
pound is made up of two parts: a 
liquid activator, and the adhesive. 
When the activator contacts the 
adhesive, a conductive bond is 
formed. 

Judging from the manual's in- 
structions, using the adhesive re- 
quires care and a steady hand, but 
using it is thejonly way to go if you 
don't have an oven for the reflow 
process. 

You can read volumes of liter- 
ature on surface-mourrt'tech- 
nology (including "A Revolution in 
\C Packaging," an article that ap- 
peared in the May 1986 Radio-Elec- 
tronics) and get a pretty good idea 
of what's important when working 
with surface-mount devices. But 
nothing beats hands-on experi- 
ence to help you get a real under- 
standing of all aspects of what's 
involved. 

Our only complaint is that the 
kit does not include any surface 
IC's. We understand why it 
doesn't — -it's impossible to know 
what IC's someone will want to use 
in a prototype circuit. But we still 
wish we could have tried our hand 
at soldering surface-mount IC's 
without having to go to another 
source for the parts. 

The SMT2Q00 sells for $348. The 
5MT1000, a version of the training 
kit that does not include any sur- 
face-mount devices, sells for $215. 
While those prices put the kits out 
of the range of someone who's 
only interested in SMT, it's a small 
price to pay for an electronics de- 
sign engineer or technician who 
needs to become involved with all 
aspects of surface mount tech- 
nology. We feel that the SMT Train- 
ing Kit serves its intended purpose 
very well. R-E 



38 



STUN GUN 



ROBERT GROSSBLATT, and ROBERT IANNINI 

Man's fascination 
with high voltages 
began with the first 
caveman who was 
terrified by a bolt of 
lightning. In more 
recent times, 
electronics 
experimenters and 
hobbyists have found 
the Tesla coil and the 
Van de Graaff 
generator equally 
fascinating. In this 
article we'll show you 
how to build a hand- 
held high-voltage 
generator that is 
capable of producing 
75,000 volts at a power 
level as high as 25,000 
watts. The stun gun 
can be used to 
demonstrate high- 
voltage discharge and 
as a weapon of self- 
defense. Before 
building one, however, 
you should read and 
pay very close 
attention to the 
warning in the 
accompanying text 
box, as well as to the 
description of 
physiological effects 
that follows. 




This experimental high-voltage 
generator can produce 75,000 
' volts at a peak power of 2b,000 
watts. 




WARNING 

THIS DEVICE IS NOT A TOY. We present 
it for educational and experimental pur- 
poses only. The circuit develops about 
75,000 volts at a maximum peak power of 
25,000 watts. The output is pulsed, not 
continuous, but it can cause a great deal 
of pain should you become careless and 
get caught between its output terminals. 
And you should never, repeat, NEVER, 
use it on another person! It may not be 
against the law in your area to carry a stun 
gun in public, but, if you use it on another 
person, you may still be liable for civil ac- 
tion. 

To help you build, test, and adjust the 
device safely, we have included a number 
of tests and checks that must be followed 
strictly. Do not deviate from our procedure. 



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Physiological effects 

So that you may understand tlic danger 
inherent in the stun gun. let's discuss the 
physiological effects first. When a high 
voltage is discharged on the surface of the 
skin, the current produced travels through 
the nervous system by exciting single 
cells and the myelin sheaths- that enclose 
them. When that current reaches a syn- 
apse connected to a muscle, it causes the 
muscle to contract violently and possibly 
to go into spasms. 

The longer contact with the high volt- 
age is maintained, the more muscles will 
be affected. If the high voltage maintains 
contact with the skin long enough to cause 
muscle spasms, it may take ten or fifteen 
minutes before the brain is able to re- 
establish control over the nerve and mus- 
cular systems. 

How much power is required to cause 
such spasms'? That's not an easy question 
to answer because, although it is rela- 
tively easy to make precise measurements 
of the power produced by a high- voltage 
device, it is difficult to rate the human 
body's susceptibility to shock accurately. 
Some obvious factors include age and dis- 
eases such as epilepsy. But the bottom line 
is simple: The only one who fools around 
with a stun gun is a fool. 

The amount of energy a device delivers 
is actually the amount of power delivered 
in a given period of time. For our pur- 
poses, it makes sense to talk about energy 
in joules (watt -seconds). Using a fresh 
9.8-volt Ni-Cd battery, the stun gun is 
capable of delivering peak power pulses 
of 25,000 watts. Actually, pulses start out 
at peak power and then decay exponen- 
tially. The length of the decay time de- 
pends on the components used in the 
circuit, the ambient temperature, the bat- 
tery's capacity, and the positioning of the 
output contacts with respect to each other. 

Assuming that the decay rate is purely 
exponential, the stun gun can produce 
about 0.5 joules of energy, provided that 
the battery is fully charged. Let's put that 
number in perspective. 

Both the Underwriter's Laboratory (in 
Bulletin no. 14) and the U. S, Consumer 
Product Safety Commission state that 
ventricular fibrillation (heart attack) can 
be caused in humans by applying 10 
joules of energy. Since the stun gun only 
generates about half a joule, you might 
think that a device that produces only one 
twentieth of the critical amount has a 
more-t ha n -adequate margin of safety. 
Don't bet on it. A brief contact with the 
stun-gun's discharge hurts a great deal, 
but it lakes only about five seconds of 
continuous discharge to immobilize 
someone completely. 

Let's compare the stun gun's output 
with a similar device, called a Tasergun, 
which appeared on the market a few years 
ago. You may have seen a film demon- 
strating just how effective the Taser could 



RT 
22 K 



C3 
25V 



RE 
39K 

H5 

mon 



m 

i 03 

2N2B46 

FW 
36S1 




Ql 
04005 



□ 1. 
IN4Q01 



RS 
100 V>. 



+ X vsv j 



R1 1K 

R2 
110124 

CI 



9V 

S1 ^L 

FIRE H 



'f 



J1 
CHARGER 



UjEUJ 



Q2 
□400 5 



J?C) 



02 

IN4001 



| HIGH-VOLTAGE 

OUTPUT 
TO ELECTRODES 



SEE TEXT 



FIG. 1— THE STUN GUN'S CIRCUIT is a multi-stage voltage step-up circuit. The G1/Q2 circuit produces 
a squarewave output of about 10 kHz, and Q3 produces 15-|ia discharge pulses at a rate of about 20 
ppm. Those pulses fire SCR1, which induces a voltage in the windings of step-up transformers T2 and 
T3. 



be as a deterrent. A foolhardy volunteer 
was paid an enormous sum of money to 
have the Taser fired at him. No matter how 
big, strong, {and stupid) the person was, 
as soon as the Taser's "darts" hit him, he 
would collapse to the ground and go into 
uncontrollable convulsions. 

The energy produced by the Taser is 
only 0.3 joules — about 60% of what our 
stun gun produces! Even so, the Taser has 
been officially classified as a firearm by 
the Bureau of Tobacco and Firearms be- 
cause it shoots its electrode "darts" 
through the air. Even though our stun gun 
doesn't operate that way. the Taser puts 
out considerably less energy than the stun 
gun. Keep those facts and figures in mind 
as you assemble and use the device. 

How it works 

The schematic diagram of the stun gun 
is shown in Fig. I. Basically, it's a multi- 
stage power supply arranged so that each 
succeeding stage multiplies the voltage 
produced by the preceding stage. The 
final stage of the circuit feeds two op- 
positely-phased transformers that produce 
extremely high voltage pulses. If that de- 
scription sounds familiar, you've proba- 
bly studied capacitive-discharge ignition 
systems — the stun gun works on the same 
principles. 

The first section of the power supply is a 
switcher composed of Ql, Q2, and the 
primary windings (connected to leads E, 
F, G,andH)ofTl. When fire switch SI is 
closed, Rl unbalances the circuit and that 
causes it to start oscillating. Since base 
current is provided by a separate winding 
of Tl (connected to leads C and D), the 
two transistors are driven out of phase 
with each other, and that keeps the circuit 
oscillating. Resistor R2 limits base drive 
to a safe value, and diodes Dl and D2 are 
steering diodes that switch base current 



from one transistor to the other. Oscilla- 
tion occurs at a frequency of about 10 
kHz. 

The switching action of the first stage 
generates an AC voltage in TFs high- volt- 
age secondary (leads A and B). The 
amount of voltage depends on the battery 
used, but a battery of seven to nine volts 
should produce 250 to 300 volts across 
Tl's secondary. 

That voltage is rectified by the full- 
wave bridge composed of diodes D3-D6. 
Capacitor C2 charges through D7 at a rate 
that is controlled by R3. 

The value of capacitor C2 affects the 
output of the stun gun. The greater the 
capacitance, the more energy that can be 
stored, so the more powerful the dis- 
charge will be. A larger capacitor gives 
bigger sparks, but requires more charging 
time, and that gives a lower discharge 
rate. On the other hand, a smaller capaci- 
tor gives smaller sparks, but a faster dis- 
charge rate. If you wish to experiment 
with different values for C2, try 3,9 p.F(as 
shown in Fig. I), 7.8 p,F, and 1. 95 p.F. 
Those values were arrived at by using one 
3.9 u.F capacitor alone, two of the same 
capacitors in series, and two in parallel. 

Meanwhile, UJT Q3 produces I5-jjls 
pulses at a rale of about 20 ppm. That rate 
is control ted by C3 and the series com- 
bination of R6 and R7. When a pulse 
arrives at the gate of SCR I, it fires and 
discharges C2. That induces a high-volt- 
age pulse in the primary windings of T2 
and T3, whose primaries must be wired 
out of phase with each other. The result is 
a ringing wave of AC whose negative 
component then reaches around and 
forces the SCR to turn off. When the next 
pulse fern Q3 arrives, the cycle repeats. 

The outputs of the stun gun appear 
across the secondaries of T2 and T3. The 
hot leads of those transformers connect to 



42 




f-vJl&ASL/-' 



OUTPUT 



J1 

CHARGER 
OUTPUT 



FIG. 2— MOUNT ALL COMPONENTS ON THE PC BOARD as shown here. Note that T2 and T3 are 
mounted off board, and that J1, C1, and D7 mount on the for! side of the board. In addition, a number of 
components mount beneath T1: D1-D6, R1, and H3. Those diodes and resistors must be installed 
before Tl. 



m Si Q2 Ol 




FIG. 3— BEND SCRI'S LEADS 90° so that the nomenclature faces up and then solder the SCR to the 
board. Also note that C3 must be bent over at a 90° angle, and that R2 is mounted vertically. 




FIG. 4— JACK J1, DIODE D7, AND CAPACITOR C1 mount on the foil side of the PC board. One terminal 
of Jt mounts to the same pad as R8, and the jack should be giued to the board with RTV (or other high- 
voltage compound} after you verify that the circuit works properly. 



PARTS LIST 
All resistors are Vi-watt, 5% unless oth- 
erwise noted. 
R1— 1000 ohms 
R2--110ohms, 1 watt 
R3— 2200 ohms, 1 watt 
R4 — 36 ohms 
R5, R8— 100 ohms 
R6— 39,000 Ohms 
R7— 22,000 ohms 

Capacitors 

C1— 10 u-F, 25 volts, electrolytic 
C2— 3.9 U.F, 350 volts, electrolytic 
C3— 1 u,F, 25 volts, electrolytic 

Semiconductors 

D1, D2— 1N4001. 50-volt rectifier 
D3-D8— 1N4007, 1000-voit rectifier 
Q1, Q2— D40D5, power transistor 
Q3— 2N2646, UJT 
SCRI— 2N4443 

Other components 

B1— 9-volt Ni-Cd battery 

S1 — SPST momentary pushbutton switch 

T1 — 12 to 400 volts saturable-core trans- 
former. See text 

T2, T3 — 50 kilo volt pulse transformer, 
0,32 joules. 400-volt primary. See text 

Note: The following components are 
available from Information Unlimited, 
P. O. Box 716, Amherst, NH 03031: T1, 
$12.50; both T2 and T3, $12.50; C2, 
$1.50; PC board, $4.50; case, S3. 50; 
case with T2 and T3 potted, $17.50; 
charger, $6.50; 9. 8- volt battery, $16.50; 
complete kit of all parts including all 
components, PC board, case, and 
charger, but no battery, $39.50. 



the output electrodes, which should be 
held securely in position about two inches 
apart, and which should be insulated from 
each other and from the environment with 
high- voltage potting compound. 

Batteries 

The stun gun can be powered with al- 
most any battery that can supply at least 
seven volts at one amp. A Ni-Cd battery 
would be a good choice; R8 and Jl will 
allow the battery to be recharged without 
removing it from the case. 

The higher the battery's voltage, the 
higher the stun-gun's output voltage. 
Most nine-volt Ni-Cd's actually have a 
maximum fully-charged output of only 
7.2 volts. However, batteries that deliver 
9.8 volls when fully charged are available 
from several sources. 

Construction 

Keep in mind the fact that the stun gun 
produces dangerously high voltages, and 
don't approach the construction of the 
stun gun with the same nonchalance with 
which you might build a light dimmer. 

The circuit can be built on a PC board 

or on perfboard. The foil pattern for a PC 

continued on page 94 



3 

03 

rn 



43 




UJWqlOTB 

PHONY "^ 

BURGLAR ALARM 

Scare off burglars without emptying your wallet with this 
simple, inexpensive electronic "scarecrow, " 



MICHAEL RINGENBERGER 



IT S A SAD COMMENTARY THAT THESE 

days a burglar alarm is becoming as com- 
mon a household "'appliance" as a re- 
frigerator or a dishwasher. But burglar 
alarms are not inexpensive. Most will cost 
a few hundred dollars, and some elaborate 
systems could cost a thousand dollars or 
more. 

If your household possessions are sim- 
ply not worth lhat kind of outlay, there is a 
very inexpensive alternative. Most bur- 
glars are burglars because it's the easiest 
way they know of to make a fast buck. 
When they look for a house to ransack, 
they try to find the easiest target. The 
trick, then, is to make your house look 
like it is protected by a sophisticated 
alarm system. That can be done for less 
than $20 with the circuit described here. 



DISARM 



-C-*9ARM 
SI 



LED U 
RED 



// 



Qi) GREEN Qy 



^ 



IC1 
LM3909 



-Her- 

16V 



"^ 



B1 



FIG. 1— IT'S NOT A REAL BURGLAR ALARM, 
but this "electronic scarecrow" can do almost 
as good a job as a real one when it comes to 
scaring away a burglar. 



HsvT 




) DISARM 



i — 6-*o 



ARM 



GREEN 



RED 



FIG. 2— THE CIRCUIT CAN BE BUILT on a tiny 
PC board. The pattern is provided in our PC 
Service section. 




FIG. 3— THE CIRCUIT SHOULD be assembled on a piece of anodized aluminum. 



An electronic scarecrow 

No burglar alarm will make your home 
absolutely burglar proof. If you have 
something a burglar wants badly, and the 
burglar is a professional, he'll find a way 
to defeat the alarm. Otherwise, an alarm's 
principal value is as an "electronic scare- 
crow, " Seeing that the house is protected, 
a burglar will move on to easier pickings. 

How does a burglar know that there is 
an alarm? Most alarm systems have their 
sensors hidden from view, so frequently 
the only sign of an alarm system is a status 
display located near the entrance. That 
display usually consists of a red and a 
green LED that show whether or not the 
system is armed. 

By now you may have guessed where 
we are headed: Since the presence of an 
alarm-status display alone is enough 
sometimes to scare off a burglar, why not 
set up a dummy display and do away with 
the rest of the system? That's precisely 

PARTS LIST 

C1 — 47 u.F, 16 volts, electrolytic 
IC1— LM3909 LED flasher 1C 
LED1— green jumbo LED 
LED2 — red jumbo LED 
S1— SPST, key switch 
B1— 1.5 volts, "C'cell 
Miscellaneous: PC or perforated-con- 
struction board, anodized aluminum pan- 
el, battery holder, wine, solder, etc. 
The following are available from En- 
berg Electronics, PO Box 55087, Indi- 
anapolis, IN 46205: Complete kit, 
including anodized aluminum cover, 
$18.95; assembled unit, $22.95; 
anodized cover, $2.50; PC board, 
$2.50. Indiana residents please add 5% 
sales tax. 



what our circuit does. Of course it won't 
give you the degree of security that a real 
alarm-system would, but its cost is much, 
much lower. 

The schematic diagram of the circuit is 
shown in Fig, 1. The circuit is extremely 
simple and is built around an LM3909 
LED flasher IC. With the value of CI 
shown, the circuit will flash an LED at a 
rate of 5.5 times-per-second. It is powered 
by an alkaline "C"-size cell; estimated 
battery life is 15 months. 

Switch SI should be a key type as is 
typically found in burglar-alarm installa- 
tions. The switch should be mounted on 
the dummy status-display's front panel to 
give the set up a more realistic look. 

Building the circuit 

The circuit is simple enough to be built 
on a piece of perforated construction 
board. If you wish to use a PC board, an 
appropriate pattern is shown in our PC 
Service section. The parts- placement di- 
agram for the board is shown in Fig. 2. 

Two construction details bear special 
mention. One is the lead length of the 
LED's, They should be W-ineh long to 
allow for flexibility when mounting the 
board (more on that in a moment). Sec- 
ondly, the lead length of CI should be kept 
to an absolute minimum. Be sure that the 
bottom of that electrolytic capacitor is 
flush with ihe board. 

The circuit is mounted on a piece of 
anodized aluminum. Size is not critical, 
as long as it is appropriate forthe task. The 
author's prototype was V/i x 4 inches. 
The other side of the aluminum piece will 
serve as the dummy status-panel. 

con I i lined on page 98 



44 



COMMUNICATIONS 



JOSEF BERNARD 

ALMOST LVERY FRbQUBMCY IN THH RF 

spectrum, from near DC to billions of 
cycles per second, is used for some type of 
communication. Indeed, at limes it seems 
as if there are almost as many communi- 
cations services as there are frequencies 
for them to occupy. And at times it seems 
that the ordering Of the different services 
that make use of the RF spectrum is pure- 



ly random. Of course it is not. There is 
usually a good reason for a service being 
located where it is. In this climb up the 
"electromagnetic ladder" we'll see some 
of the varied services that make use of the 
RF spectrum, and learn why they are in 
their particular niches. 

Meters and hertz 

You no doubl have noticed that the lo- 
cation of a signal in the RF spectrum is 



often specified in hertz, but that some- 
times it is specified in meters. Meters are 
a unit of distance, as you might expect. 
What is being measured is the wavelength 
of the signal. A wavelength is the distance 
from one point on one cycle to the corre- 
sponding point on the next. See Fig. 1. On 
the other hand, the hertz (abbreviated Hz) 
is a unit of frequency. It indicates how 
many cycles occur in one second. One 
hertz is equal to one cycle-per-second. 



From DC to Microwave 



On this guided tour of the RF spectrum we'll see what 
types of communications take place 
where, and why. 




m 



45 



I 




t [SECONDS! 



FIG. 1— THE WAVELENGTH AND FREQUENCY of a wave are related through f - e/K. Therefore a wave 
with a frequency of one cycle-per-second (1 hertz) would have a wavelength of 300,000 kilometers. 



The relationship between the two mea- 
sures is simple, and if you know one you 
can easily determine the other. That's be- 
cause the wavelength of an electromag- 
netic wave is inversely proportional to its 
frequency— that is, the longer the wave- 
length , the lower the frequency. The rela- 
tionship between frequency and wave- 
length is given by/=c/A, where/ is the 
frequency in Hz, A is the wavelength in 
meters, and c is the speed of light in 
meters-per-second. 

Obviously, either measure can be used 
to specify the location in the spectrum of 
an RF (Radio Frequency) signal com- 
pletely. Why, then, are some signals usu- 
ally specified in meters while others are 
specified in hertz? 

The main reason is simply tradition. A 
general rule-of-thumb is that in regions of 
the spectrum that have been in use the 
longest — for the most part since before 
World War II — the common usage is to 
describe a signal using meters. Thus, the 
shortwave broadcast bands, and the 
"high-frequency" bauds used by amateur 
radio operators, are still usually referred 
to in terms of their wavelengths in meters 
(25, 31, 40, etc.), and shortwave re- 
ceivers, which these days frequently are 
called "communications receivers," have 
their dials scaled in meters. 

On the other hand, bands in the more- 
recently exploited part of the spectrum 
usually are referred to by the frequencies 
used. An exception to that is in the portion 
used by radar, and for terrestrial-micro- 
wave and satellite communications, 
where terms such asC-band, Ku-band, ri- 
band, X-band, and the like abound. To 
confuse matters, those designations have 
nothing to do with either frequency or 
wavelength. 

Starting at the bottom 

The RF spectrum runs from 10,000 Hz 
(10 kHz) up beyond 300 gigahertz (300 x 
I0 9 Hz). The lower limit is within the 
realm of sound; the upper limit borders on 
infrared light. 

At the very bottom of the RF spectrum 
are frequencies of tens or hundreds of 
kilohertz, with corresponding wave- 
lengths of thousands of meters (at 100 kHz 
an electromagnetic wave has a wavelength 



of three kilometers, or about 1.8 miles). 
There, the ground -wave phenomenon pre- 
dominates; radio waves tend to hug the 
earth rather than bounce off the 
ionosphere as they do at higher frequen- 
cies. That low- frequency region used to be 
the domain of the early radio pioneers. 



300GH?- 




EHF 



30GHz- 



SHF 



3GHz- 



UHF 



300MHz- 



VHf 



o 

* 30MHz- 



HF 



3MHi- 



MF 



:bokh.> - 



IF 



30 KH/- 



The selection of those frequencies was not 
made freely; the mechanical spark-gap 
communications sets used by Marconi 
and others were not capable of generating 
higher frequencies. 

With the spark-gap age long behind us, 
those lowest frequencies are now used pri- 
marily for navigational purposes and for 
long-range military communications with 
submarines (although in general water is a 
poor propagation medium, best results are 
achieved at lower frequencies). Low and 
very low frequencies are not used widely 
for communications because of the prob- 
lems encounlered when attempting to use 
those frequencies to convey even moder- 
ately complex data. Remember, as the fre- 
quency of the modulating information 
increases, so does the bandwidth of the 
resulting signal. The problem is similar to 
that encountered when trying to transmit 
computer data over standard telephone 



SPACE: 



SATELLITES & OTHER SPACE 
FiXED & MOBILE COMMUNICATIONS 



TV BROADCAST 

CELLULAR TELEPHONE [AND OTHER 

FIXED & MOBILE COMMUNICATIONS! 

MICROWAVE RELAY 

SATELLITES 
AMATEUR RADIO 



- 



TV &FM BROADCAST 

FIXED & MOBILE COMMUNICATIONS 

AMATEUR RADIO 



INTERNATIONAL SHORTWAVE 

AMATEUR RADIO 

TIME (WWV1 

CB 

FIXED & MOBILE COMMUNICATIONS 



AM BROADCAST 
AMATEUR RADIO 



NAVIGATION 
SUBMARINE COMMUNICATIONS 



NAVIGATION 
SUBMARINE COMMUNICATIONS 




THE RF SPECTRUM extends from 10 kHz, which is within the realm of sound, to 300 gigahertz, which 
borders on infrared light. 



circuits. Beyond a certain speed of trans- 
fer, the bandwidth of the signal exceeds 
the capability of the telephone lines. At 
low and very-low frequencies, it doesn't 
take much modulation to eat up vast 
stretches of the spectrum. And even low- 
frequency earth-hugging navigational 
beacons are being supplanted by newer 
satellite-based systems. 

Medium waves 

The MW (Medium Wave) region 
stretches from 300 kHz to 3 MHz, The 
best known part of that region, at least to 
most of us, is the AM broadcast band. It 
occupies the frequencies from approx- 
imately 540 to 1600 kHz. 

At MW frequencies an interesting phe- 
nomenon begins to occur. That is, the 
ground- wave propagation of the low fre- 
quencies begins to give way to sky-wave 
propagation. See Fig. 2. In sky-wave 
propagation, signals no longer follow the 
contours of the earth. Instead they travel a 
line-of-sight path to the horizon, and out 
into space. Part of the signal may be re- 
flected back to earth by the ionosphere, a 
region of the atmosphere made up of 
charged particles. The amount of reflec- 
tion depends on several factors, but pri- 
marily on the frequency of the 
transmission and the state of the 
ionosphere itself. The state of the 
ionosphere changes depending on the 
time of day (during the daylight hours the 
sun is bombarding the atmosphere with 
energy that can cause ionization; at night, 
the amount of ionization decreases) and 
the state of solar activity (solar flares and 
the like can also pour tremendous 
amounts of energy into the atmosphere). 
Anyone who has listened to an AM broad- 
cast radio has heard the effects of the 
changing state of the ionosphere. During 
the day, reception is limited pretty much to 
local stations, but after the sun has set 
stations from hundreds or even thousands 
of miles away can be heard. 

Short waves 

The boundaries between the segments 
of the RF spectrum are not clearly de- 
fined, but somewhere around 200 kHz 
(150 meters) we find the beginning of the 
shortwave region of the spectrum. That 
region extends to beyond 30 MHz (10 
meters). The band between 3 and 30 MHz 
is also known as the HF (rVigh Frequency) 
region. At those frequencies, the reflec- 
tive properties of the ionosphere are the 
strongest. 

Until the advent of the communications 
satellite, all long-distance radio commu- 
nications look place on the shortwave 
bands, and those bands are still full or 
activity; not everyone, after all, can afford 
a satellite earth station. 

Note that we are still in the pre-World- 
War-11 part of the spectrum, and thus we 
most often speak in terms of wavelengths 



IONOSPHERE 



GROUND WAVES FOLLOW 
CURVE OF EARTH 



SKY WAVES TRAVEL IN STRAIGHT LINES 
AND MAY BE REFLECTED BY IONOSPHERE 





EARTH 



FIG. 2— GROUND WAVES, usually associated with low frequencies, hug the earth. Sky waves resulting 
from higher-frequency sources travel in straight lines. Depending on their frequency, and on other 
conditions, the waves may either travel out into space, or be reflected back to earth by the ionosphere. 



rather than frequencies. Thus SWL's 
(Short Wave Listeners) refer to interna- 
tional broadcasts in the 25-, 31-, or 49- 
metcr bands, and amateur radio operators 
work the 80-, 20-, or 15-meter bands. 

The characteristics of the shortwave 
bands change as they increase in frequen- 
cy. In the lower reaches of the shortwave 
portion of the spectrum, propagation is 
primarily ground wave during the day and 
sky wave during the evening, much like 
the AM broadcast band that is located not 
far below in frequency. Around 30 meters 
(10 MHz) or so, things begin to turn 
around and there is good long-distance 
sky-wave propagation during the day. but 
the bands shut down at night as there is 
only short range ground- wave communi- 
cation. 

Propagation on the shortwave bands 
varies not only with the time of day, but 
also with the 1 1-year sunspot cycle. Over 
a period of 1 1 years, the degree of sunspot 
activity rises to a peak, and then falls off 
considerably. No one is quite sure exactly 
why that happens, but when sunspot ac- 
tivity is low, as it is now, the higher fre- 
quencies become useless for long- 
distance communications. There simply 
is no skip. As sunspot activity gradually 
increases, the ionosphere is restored, and 
long-distance communications again be- 
come possible on the higher shortwave 
frequencies. Tire ncxl peak in the sunspot 
cycle is expected around 1991. 

International broadcast services, usu- 
ally operated by the government of one 
country or another, abound in the short- 
wave bands. Sometimes they carry pro- 
gramming for citizens or subjects of those 
countries to keep them abreast of develop- 
ments at home. Frequently too, those ser- 
vices arc used to disseminate political 



■ 



r*d 



propaganda — sometimes subtle, and 
sometimes not so subtle; two such ser- 
vices are Radio Moscow and the Voice of 
America. Broadcasts from those interna- 
tional services go on 24 hours a day, 
changing frequencies and transmitter sites 
to obtain the best propagation conditions 
to various parts of the world. 

Many amateur radio operators, or hams 
as they are frequently called, make exten- 
sive use of shortwave frequencies to lalk 
to other hams around the country and 
around the world. Frequently, there are 
contests, with elaborate rules for scoring, 
in which hams accumulate points for con- 
tacting as many stations as they can — the 
farther away and the harder to find, the 
better — in a given period. 

(An aside in the interest of amateur 
radio; The primary purpose of that '"hob- 
by" — some would call it a way of life — is 
to engage in two-way communications 
with other hams. If you just listen — 
whether it's with a communications re- 
ceiver or with a VHF or UHF scanner — 
you're an SWL. When the news services 
reported last year that "any ham with the 
proper equipment could have listened in 
on the president's unscrambled con- 
versations from Air Force One," they 
should have said, instead, "any listen- 
er ... " Eavesdropping is not the intent of 
the amateur radio service.) 

There's a lot more on the shortwave 
bands. Although there has been a shift to 
satellites, with their greater reliability, 
many commercial services still depend on 
those hands. Time services, such as 
WWV, are found at several places on the 
HF bands, transmitting accurate time and 
other information around the clock. Much 
international news and weather informa- 
tion is sent on the shortwave bands by 



77 






radioteletype (that "jingle-jingle" sound 
you hear often on the shortwave bands). 
Many governments maintain contact with 
their embassies or consulates abroad by 
shortwave, and the astute observer can 
spot their "antenna farms" atop buildings 
in major cities. 

Another shortwave service, familiar to 
just about all. is the Citizens' Band (CB) 
service located at around 27 MHz. the old 
II -meter ham band. While it's too late to 
do anything about it at this late date (about 
30 years too late), 27 MHz was not a wise 
place to locale CB. That service was in- 
tended for short-range, local use but. as 
many a CB-er and ham can tell you, when 
conditions are right there is no better place 
in shortwave for catching the ionospheric 
"skip" and talking to stations all over the 
world, even with just a few watts of output 
power. (Skip is ham and SWL slang for 
long-distance sky-wave communica- 
tions). There is talk of opening up a cit- 
izens' band around 900 MHz. and that 
would make a lot more sense, as well as 
for shorter antennas! (For another view 
see "The New World of Communica- 
tions," which immediately follows this 
story. ) 

Very high frequencies 

Once above 30 MHz or so, we enter the 
Very Wigh Frequency (VHF) realm. Be- 
cause that portion of the spectrum, as well 
as the portions above it, were not ex- 
ploited until after World War II, signals 
there are generally specified in terms of 
frequency rather than wavelength. (Ex- 
ceptions to that are the six- and two-meter 
amateur bands.) Except at the very bot- 
tom of the VHF region, propagation by 
skip is rare, and all communications are 
line-of-sight, or about as far as the hori- 
zon, depending on the height of the trans- 
mitting and receiving antennas. Max- 
imum ranges of 50 to 60 miles are typical. 

Here are found the FM broadcast band, 
the VHF (naturally) television channels, 
all sorts of local mobile-communications 
services (including police and fire depart- 
ments, mobile telephones, business com- 
munications such as taxis and local 
truckers, airplane-to-airport communica- 
tions, and many government and military 
services). Because the communications 
range is only line-of-sight, those frequen- 
cies are ideal for local services and can be 
reused time and again at fairly short geo- 
graphic intervals. 

The assignment of the frequencies used 
for television broadcasting is interest- 
ing — there are two VHF-TV bands. The 
lower one starts at 54 MHz for Channel 2; 
there used to be a Channel I but it disap- 
peared a long time ago ( For more informa- 
tion see "Whatever Happened to Channel 
I" in the March 1982 issue of Radio- 
Electronics). That band continues up to 
to 88 MHz, the top of Channel 6, There is 
then a gap of 86 MHz, which is used by 



the FM broadcast service (between 88 and 
108 MHz), among others. The VHF-TV 
channels begin again at 174 MHz (Chan- 
nel 7) and continue to 216 MHz, which is 
the top of Channel 13, the last VHF chan- 
nel. That gap between the upper and lower 
VHF-TV bands explains why, if you live 
in a fringe area. Channel 7 or 8 may be 
more difficult to receive than Channel 5 or 
6. A! higher frequencies it is more diffi- 
cult (and more expensive) to build sen- 
sitive receiving equipment, and the effi- 
ciency of old antennas and feedlines falls 
off. 

Almost all of us have witnessed the 
"Venetian blind" effect on our TV sets. It 
is caused by VHF skip, which usually 
takes place in the spring and fall. The 
effect is caused by the reception of two 
TV stations on the same channel. One 
station is your local one, while the other 
might be located hundreds of miles away. 
T^he horizontal bars that give the venetian- 
biind effect its nickname are the result of 
the two signals interfering with one an- 
other. If the bars seem to move up or down 
the screen, it's because the horizontal- 
sync frequencies of the two stations aren't 
exactly the same. It takes just a fraction of 
a percent of difference at 15,734 kHz (the 
standard horizontal-sync frequency) to be 
noticeable. That type of interference is 
analogous to beat notes at audio frequen- 
cies or diffraction patterns in light. 

Many people have the impression that it 
is the nature of FM that limits the range of 
broadcasts made using that type of modu- 
lation. That is simply not true! The reason 
for the limited range of FM broadcasts is 
that the frequencies assigned to that ser- 
vice are restricted to line-of-sight propa- 
gation. Frequency modulation is actually 
far superior to AM — not only in resis- 
tance to atmospheric noise, but in resis- 
tance to other types of interference, as 
well as in resistance to fading. It's just that 
by the time the usefulness of FM was 
recognized, the lower frequencies were all 
occupied. Perhaps that's just as well — the 
20- MHz spread of the FM broadcast band 
allows for plenty of wideband stations 
transmitting high-quality audio. 

Ultra high frequencies 

Starting at about 300 MHz and extend- 
ing to about 3,000 MHz is the UHF (Ultra 
//igh Frequency) band, perhaps best 
known because of the TV channels found 
there between 470 and 890 MHz. Until 
the late 1950's, those frequencies were 
hardly used at all because the cost of 
building transmitting and receiving 
equipment for that part of the spectrum 
was just too high. In fact, until just a few 
decades ago, virtually all the frequencies 
in that band and the ones higher in fre- 
quency were part of the FCC's legacy to 
amateur radio. Amateurs, it was hoped, 
would learn how to tame those "esoteric" 
regions of the RF spectrum. 



These days, UHF is pretty much an 
extension of the VHF band. Many of the 
services found on VHF also now have 
allocations in the UHF band. Those in- 
clude the land mobile services (especially 
cellular telephones and pagers, which 
have been assigned what was formerly the 
top of the UHF-TV band), UHF televi- 
sion, and government agencies (police, 
fire, etc.). 

Other than the fact that the VHF fre- 
quencies are just about completely oc- 
cupied, UHF offers a significant advan- 
tage to those services where hand-held 
receivers and/or transmitters are com- 
monplace. That is, UHF communications 
gear, especially the antenna (remember 
antenna length is dependent on wave- 
length), can be made much smaller. 

As an aside, handheld transceivers (a 
transcevier is a combination transmitter/ 
receiver) are commonly called walkie- 
talkies, but the proper term is "handie- 
talkie" (because it fits in your hand), A 
walkie-talkie is actually defined as a 
transceiver that you can carry around with 
you — usually strapped to your back or 
slung over your shoulder on a strap — -to 
leave your hands relatively free. The term 
"creepie-peepie, " for a portable TV-cam- 
era/transmitter combination, never caught 
on (and that's probably a good thing). 

Incidentally, you can tell whether a 
handie-talkie is operating on VHF or 
UHF by its "rubber duckie" antenna. If 
it's about as thick as a finger, the unit is for 
VHF; if it's about the thickness of a wire, 
it's for UHF. 

Once we get to the UHF band, we are 
dealing with frequencies that begin to ap- 
proach those of light. Not surprisingly, 
then, signals here begin to acquire some 
of the properties of light. One of the most 
common examples of that is the deteriora- 
tion of UHF-TV reception during rainy 
weather. That happens because raindrops 
tend to block the radio waves, just as they 
do light, and fewer and fewer get through 
as the distance between transmitter and 
receiver increases. 

Super high frequencies 

While the microwave band "officially" 
begins at about 250 MHz, the term micro- 
wave is now popularly used to describe 
signals in the i'uper H)gh Frequency 
(SHF) region, above 3000 MHz. Here it is 
no longer convenient to refer to frequen- 
cies in terms of megahertz; instead we 
speak in terms of gigahertz, or billions of 
cycles per second. While wavelengths 
here are still tar longer than those of light, 
they are also short enough to begin ex- 
hibiting many more of the properties of 
light. At the upper end of the SHF band, 
30 GHz, wavelengths are as short as a 
couple of inches. Like light, microwaves 
travel in straight lines. They are easily 
reflected by even small metallic surfaces; 
continued on page 53 



BENN KOBB* 

THE 800-MHZ BAND, REGARDED AS THE 

last feasible band lor mobile radio, is the 
subject of some the most heated contro- 
versies in the communications world. In 
dispute are who should have the right to 
transmit in that band, and even who 
should have the right to listen to those 
transmissions. 

This article will describe some of the 
current and proposed radio services in the 
800-MHz band. We'll also see how the 
battle for control of 800 MHz may affect 
the future of communications electronics. 



Cellular telephone 

If you live in one of the more than 100 
U.S. cities that have cellular telephone 
service, you may have noticed that the 
business pages of your local newspaper 
have become inundated with advertise- 
ments for cellular phones. In an effort to 
relieve the congestion that had plagued 
conventional UHF mobile- phone service 
for years, the FCC in 1983 opened the 
825-845 and 870-890-MHz bands to cel- 
lular systems. In each market, one 20- 
MHz band is allocated to a "wireline" 
carrier affiliated with the telephone com- 
pany that serves the area, while the other 



The New World 
of Communications 



20 MHz is allocated to an independent 
"non- wireline" carrier. 

Conventional mobile-phone systems 
typically use a single, high-power trans- 
mission site and fewer than 20 channels to 
cover an area. In contrast, cellular sys- 
tems operate through a network of many 
low-power "cell" sites and hundreds of 
channels. Cell sites can be identified by 
their towers, which typically sport pecu- 
liar, triangular antenna platforms. 

As a customer engaged in a eel hilar call 
drives from the coverage area of one cell 
into that of another, changes in signal 
strength trigger an automatic hand-off of 
thecal! from one cell to the next. Ideally, 
at worst the user hears only a split-second 
gap in conversation while his mobile unit 
switches by remote command to the chan- 
nel required by the next cell. 

A typical large-city cellular carrier uses 
20 or 30 cell sites, all connected via land- 
line (telephone line) or microwave to a 



The battle lines have been drawn 
for the fight over the last frontier 
in personal communications. 
In this article we'll learn more 
about that fight, and the prize 
that hangs in the balance. 




I 




EACH CAR REQUIRES 
A SEPARATE CHANNEL 



IN A CONVENTIONAL MOBILE TELEPHONE SYSTEM, only a single base station is used to cover the 
entire service area. 




IN THE CELLULAR SYSTEM the service area is divided into smaller "cells." Each cell has its own low- 
power base station, called a cell site. 



central Mobile 7elephone Switching Of- 
fice (MTSO). Essentially a telephone ex- 
change, the MTSO transmits and receives 
calls between the cellular network and the 
public telephone-network. 

Frequencies can be re-used several 
times within a cellular system. That fea- 
ture is what gives cellular its widely- 
touted spectrum efficiency. Also, the cel- 
lular system has a built-in growth mecha- 
nism. If the communications traffic in a 
particular cell becomes too much for it to 
handle, the cell can be split into smaller 
cells, freeing additional channels to serve 
customers without the need to actually 
expand beyond the already-allocated 20 
MHz. 

In theory, cell-splitting was designed to 
help the cellular industry serve larger 
numbers of customers without the need 
for more frequencies. In practice, things 
have not worked out all that well. Major- 



market cellular carriers have split cells to 
some extent, but the process is expensive. 
To split a cell, outlays of hundreds of 
thousands of dollars are required for site 
acquisition, engineering, and con- 
struction. Further, there have been many 
instances of local opposition to new tower 
construction. That opposition has most 
often been based on aesthetics or the per- 
ceived dangers of RF radiation. Because 
of all of that, carriers have returned to the 
FCC for more channels after all. 

The radio spectrum, however, is a very 
scarce resource. Only a few megahertz 
remain unused at 800 MHz, and the FCC 
has found itself faced with many compet- 
ing claims for that piece of the spectrum. 
Alter considering the claims, the Com- 
mission tentatively allocated an addi- 
tional 12 MHz to the cellular service, even 
though it appears that the additional spec- 
trum is only needed by a handful of car- 



riers in the nation's largest cities, and that 
most cellular systems won't even need to 
use all of their existing 20 MHz. 

Other countries that have cellular ser- 
vice arc facing a similar dilemma. Should 
more spectrum be granted to cellular, with 
its analog FM technology, or should the 
airwaves be conserved for modulation 
techniques that could bring consumers ex- 
citing new services and better spectrum 
efficiency? Several European countries 
that already have FM cellular have decid- 
ed to conserve parts of the radio spectrum 
for a futuristic project known as the Pan- 
European Digital Mobile Telecom- 
munications Network. 

That plan promises to bring European 
consumers a miniature, handheld digital 
communicator that could eventually re- 
place the mobile telephone and the radio 
pager, and that could transmit and receive 
voice and text, as well as images. Tests are 
already underway in Sweden and Ger- 
many of competing time-domain and fre- 
quency-domain multiplexed digital-radio 
systems. Such systems offer greater chan- 
nel capacity and flexibility than existing 
systems. 

Will digital mobile-radio eventually 
take the place of analog FM in the United 
States? The future depends in large part 
on whether the FCC grants more of the 
spectrum for FM systems or conserves 
some of it for more spectrum-efficient 
technologies. With heavy investments in 
FM, substantia! incentives must emerge 
for industry in this country to convert to 
digital. A successful deployment of digi- 
tal radio in Europe could provide that 
needed incentive. 

Mobile satellite 

Cellular telephone is essentially an ur- 
ban technology. That is, an expensive net- 
work of cells and switching centers is 
necessary to provide cellular service, and 
only those markets with sufficient popula- 
tion and business activity can profitably 
support cellular systems. What about the 
rest of the country? To serve what it view- 
ed as a large, untapped market for mobile 
communications in the rural U.S. , NASA 
in 1982 announced an ambitious proposal 
for a Mobile .Satellite Service (MSS) to 
provide two-way radio, paging, mobile 
telephone, data, and position-location 
services to vehicles across the country. A 
very similar program is underway in Can- 
ada, where widely separated remote pop- 
ulations could benefit greatly from a 
mobile satellite. 

A dozen companies agreed with the 
basic concept and forwarded applications 
to the FCC for licenses to launch mobile 
satellites. NASA even agreed to provide a 
free ride on a Space Shuttle Tor the win- 
ning applicant's satellite, in return for 
communication services. {Thai, of 
course, was before the Challenger disas- 
ter; that incident will considerably delay, 



if not jeopardize, she MSS program, as 
well as many others. — Editor) Satellite 
entrepreneurs projected markets in the 
millions of units for vehicular, transporta- 
ble, and, eventually, hand-portable satel- 
lite radios. Of course, the cost of 
implementing MSS will be "astronomi- 
cal;" one applicant estimated its startup 
cost to be in the vicinity of $700 million. 

The FCC tentatively allocated 821-825 
and 866-870 MHz to MSS in November, 
1984. No licenses have been granted, 
however, because that proposed allocation 
is the target of intense lobbying in Wash- 
ington by trade associations representing 
the two-way radio industry and the na- 
tion's police, fire, and emerge ncy-rnedi- 
cal radio users. Those users insist that 
their need for additional channels far out- 
weighs any public benefit that might come 
from MSS. Recent Congressional action 
requires the FCC to give top priority to 
public-safety communications in making 
spectrum decisions. Aspiring mobile-sat- 
ellite entrepreneurs argue instead that 
MSS will help to fill the need for public- 
safety radio, and that metropolitan public- 
safety agencies could make more use of 
cellular systems to meet their communi- 
cation needs. 

The MSS debate has escalated beyond 
the public safety vs. high-tech arena, and 
has entered the rural vs. urban and even 
international arenas. Several influential 
congressmen have lined up firmly behind 
MSS as the answer to under-served rural- 
communication needs, while others argue 
just as strenuously that urban areas, facing 
severe spectrum shortages, need the 800- 
MHz band for police and fire radios. 

As a way out of the 800-MHz MSS 
dilemma, many proponents are pushing 
to kick MSS upstairs to the 1.6-GHz L- 
band where land-mobile stations do not 
operate. The L-band technology, they be- 
lieve, will result in lower costs for satellite 
radios. In fact, INMARSAT, the //Verna- 
tional MAfiitinic SATellite Organization, 
has just introduced a shoebox-sized L- 
band mobile satellite-communicator for 
ships of any size — even the smallest ca- 
noe. Expected to cost well under $5000. 
the unit sends and receives error-free al- 
phanumeric messages through the IN- 
MARSAT satellite system anywhere in 
the world, 

Canada, with its substantial commit- 
ment to an 800-MHz MSS, is having to 
reevaluate its frequency selection. If the 
U.S. moves ahead with an 800-MHz 
MSS, the two nations' systems will be 
compatible, each picking-up the other in 
the event of a malfunction. On the other 
hand, should the U.S. use the 800-MHz 
band instead for regular police and lire 
radios, the Canadian satellite could easily 
interfere with and receive interference 
from U.S. users. The FCC has given Can- 
ada and international telecommunications 
authorities official notice that the U.S. 
desires to use the L-band for MSS. 



Radio-determination satellite 

A parallel development to MSS is the 
fiadio-Determination Satellite Service 
(RDSS) recently approved by the FCC. 
Originally proposed by physicisl-pilot- 
science writer Gerard O'Neill as a naviga- 
tion aid for aircraft, the RDSS service 
would pinpoint the location of any user in 
an instant and enable the user to send and 
receive short alphanumeric messages via 
satellite from a palm-sized device ex- 
pected to cost around $500. 

Although marine-, aviation-, and land- 
transportation interests are seen as major 
customers for RDSS, O'Neill's company, 
Geostar Corp. of Princeton, NJ, envi- 
sioned the system being tised also by pe- 
destrians who could signal for help if they 
witnessed a crime, accident, or other 
emergency. Geostar weathered lengthy 
legal and technical battles at the FCC in 
order to have the RDSS service approved. 
The Commission concluded that there is a 
need for RDSS, and allocated spectrum to 
it in the 1610-1626. 5-, 2483-2500-, and 
5117-5183-MHz bands. The next step is 
for Geostar and several other prospective 
RDSS companies to complete their fund- 
ing and begin construction and launch of 
the satellites. How much money will they 
have to raise? The business plans submit- 
ted to the FCC indicate an average re- 
quired investment of $300 million to start 
commercial RDSS operation. 

Communications privacy 

If you're a radio amateur, shortwave 
listener, or scanner enthusiast, chances 
are you've heard of the Electronic Com- 
munications Privacy Act (ECPA), a bill 
pending before the House and the Senate 
that could have a dramatic impact on hob- 
by radio listening if enacted into law. 
Where did the ECPA come from and how 
will it affect radio communications'? 

Essentially, the ECPA is an attempt by 
concerned congressmen to bring federal 
wiretap laws up to date to accommodate 
new technology, especially electronic 
mail and mobile-telephone systems. As 
you may know, existing provisions of the 
Communications Act of 1934. as 
amended, prohibit the divulging or mis- 
use of any information you may obtain by 
monitoring a communication not intend- 
ed foi you. It is that feature of existing law 
that permits SWL's and scanner listeners 
to engage in their hobby without fear of 
criminal prosecution — as long as they 
don't divulge what they hear or use the 
information for personal gain or criminal 
purposes. 

The emergence of computer crime, of 
satellite-TVRO technology, and of cel- 
lular-telephone systems have led various 
trade associations to lobby congressmen 
to support legislation that would have a 
broad application to penalize illegal inter- 
ception of any electronic communica- 
tion—whether transmitted by wire, liber 



optics, cellular, satellite, or a not-yet-in- 
vented communications system. Accord- 
ingly, two similar bills were introduced 
providing stiff penalties for unauthorized 
interception of communications. Those 
hills are aimed not at amending the Com- 
munications Act, but at the wiretap provi- 
sions of the Omnibus Crime Control and 
Safe Streets Act. 

The sponsoring trade associations, in- 
cluding the Cellular Telecommunications 
Industry Association, the Electronic Mail 
Association, and others, were generally 
satisfied with the wording of the proposed 
legislation which would, it appeared, pro- 
tect their constituencies from invasion of 
privacy. 

Radio-hobby organizations, however, 
were aghast at the sometimes draconian — 
and other times just plain confusing — 
wording of the bills. For example, the 
ECPA initially would have made it illegal 
to listen to a signal emitted by a radio in a 
vehicle but gave the green light to listen- 
ing to a hand-held radio. Fortunately, that 
portion was later removed. The status of 
amateur-radio "auto patch" or telephone 
interconnection was extremely vague; al- 
though the bills "exempted" amateur ra- 
dio from their privacy protections, they 
did make it illegal to listen to telephone 
calls. That issue is still unclear in the 
current version of the bills, although most 
observers interpret the language to mean 
that you won't be criminally liable for 
listening in on a ham's autopatch call. 




UNDER SOME PROVISIONS of the ECPA, if 
passed, the legal use of scanners and other 
communications gear would be curtailed. 

The bills appeared to make listening to 
marine, aviation, or governmental sta- 
tions illegal, too. After lengthy hearings 
that included testimony from the Amer- 
ican ftadio ffelay League (ARRL) and the 
Association of Worth American /?adio 
Clubs (ANARC), changes were intro- 
duced in the legislation to make it at least 
somewhat more palatable to radio hob- 
byists and amateurs. 

The current version of the House bill. 
HR 3378, permits monitoring of most of 
the radio services you might hear on a 
scanner or shortwave receiver — as long as 
those services are not scrambled or en- 
crypted. Unfortunately, the mere recep- 
tion of a scrambled radio signal — even if 



I 




you do not unscramble or demodulate the 
signal — will carry criminal penalties, at 
least under the current version. Un- 
authorized reception of a cellular tele- 
phone conversation could result in a fine 
of up to $500 and up to six months in jail. 
That provision was adopted even though 
cellular telephones can be received on 
800- MHz scanners, service monitors, 
spectrum analyzers, and on many TV sets 
and videocassette recorders when they arc 
tuned above Channel 80. If you recall, in 
the 1970's the FCC re appropriated the fre- 
quencies for the little-used UHF Channels 
70 through S3 and reassigned them to 
mobile-communications services. Part of 
that allocation went to cellular telephone. 

Monitoring of other common-carrier 
communications, such as microwave ra- 
dio, paging, or international marine-radi- 
otelephone services, would carry stiffer 
penalties. However, listening to cordless 
telephones would be exempt from any 
criminal sanctions. 

How those proposed laws would affect 
satellite-TVRO owners is anything but 
clear at this point. Legislators involved in 
the ECPA have publicly conceded that 
they don't want the bills to have any effect 
one way or the other on satellite-TVRO 
owners, even though monitoring of satel- 
lites is specifically prohibited by the legis- 
lation unless the material received is 
intended for use by television broadcast- 
stations. 

The final legislation, if adopted by 
Congress and signed by the President, 
could of course end up being more, or 
less, restrictive than HR 3378. Watch the 
What's News, Satellite News, and Video 
News columns in Radio-Electronics for 
any late-breaking information on the 
ECPA, Hopefully, you won't have to retire 
your communications receiver and take 
up butterfly collecting. 

Personal radio 

The Citizens fiand (CB) radio service 
operates at 27 MHz. However, the origi- 
nal "Citizens Radio Service" occupied 
the entire band between 460-470 MHz 
when it was created in the 1940's, The 
FCC eventually took most of the UHF 
band from Citizens Radio and reallocated 
the frequencies to business and industrial 
radio-services, turning the old 11-meter 
ham band over to CB as a sort of compen- 
sation for the loss. 

A sliver of that 460-MHz band — eight 
channels — still exists for citizens radio 
(now called "personal" radio) at UHF, 
and it is in that band that the "CB of the 
future" may find a home. 

To understand what may happen to the 
UHF band, and how its fate is tied to the 
800-MHz proceedings, it's necessary to 
backtrack to 1975 when the CB boom was 
hitting its peak. Millions of Americans 
were installing CB's in homes and cars, 
and legitimate users were being crowded 




DURING THE CB BOOM of the mid 1970s millions of Americans were Installing CB gear, such as the 
unit shown here, in their cars and homes. 



out by those "experimenting" with skip 
and using illegal amplifiers. The FCC was 
experiencing one of the biggest headaches 
in its history: A runaway radio service that 
was impossible to control and license 
effectively. 

The commission at that time received 
several proposals to initiate a new CB- 
radio service at 220 MHz in order to take 
some of the pressure off of the 27-MHz 
band. The 220-MHz band was the domain 
of amateur-radio operators, and they 
strongly objected to that reallocation, pre- 
dicting that the result would be even more 
on-the-air chaos. 

Hams were successful in keeping 220 
MHz. The FCC's eyes turned to establish- 
ing the new CB service at 800 MHz, and 
in 1979 the agency began a large-scale 
inquiry into how that could be accom- 
plished. Consultants were hired. Thou- 
sands of questionnaires were distributed. 
Comments were received from industry 
and the public. 

In I983, the General Electric company 
filed a request with the FCC to expedite 
the process of authorizing a new service at 
800 MHz. It reported the results of its 
program to develop what it called a Per- 
sonal /?adio Communications Service 
(PRCS), a highly advanced base- and 
mobile-radio system for the family or 
small business user. The projected cost for 
both the base and the mobile unit was 
under $500. That FM system used selec- 
tive addressing and microprocessor-con- 
trolled channel selection to assure users of 
a free channel and to reduce interference 
to the maximum extent possible. 

PRCS was a flexible system that would 
have lent itself well to travelers- assistance 
and motorist-safety applications. PRCS 
had, however, one particular capability 
that represented both its most exciting fea- 
ture and its downfall. PRCS could be used 
as a mobile telephone. The user could 
make telephone calls from a mobile or 
portable unit, through one's own base sta- 
tion at home, connected to the telephone 
line in a similar manner as an answering 



machine. No special charges would ap- 
ply, unless the user chose to operate 
through an optional local-repeater system 
for greater range. Repeater tees were ex- 
pected to be about $10 a month. 

The competition PRCS could have 
given to the then-infant cellular-telephone 
industry was considerable. Unlike cel- 
lular, PRCS was capable of direct mobile- 
to-mobile communication and through- 
thc-home mobile-telephone calling at no 
cost. Attorneys for General Electric's 
competitors are unwilling to sacrifice any 
of the precious 800-MHz spectrum to a 
consumer-oriented personal-radio ser- 
vice. So they filed mountains of docu- 
ments with the FCC claiming that PRCS 
would be beset by massive interference 
and that there was little or no measurable 
demand for the service anyway, even 
though GE was attracting interest as a 
result of PRCS demonstrations. 

Faced with competing demands for 
800-MHz. and contending that the high- 
er-priced cellular telephone could meet 
most of the needs projected for the PRCS , 
the FCC elected not to authorize PRCS 
and to let the experimental authorizations 
for the small number of existing PRCS 
stations expire. A petition for recon- 
sideration of that action, filed by the Per- 
sonal Radio Steering Group Inc. of Ann 
Arbor, Ml, is still pending. 

The FCC did not forget about the prom- 
ise of personal radio and the possibility of 
creating some kind of improvement in 
CB. In January of this year, the Commis- 
sion returned to those 8 460-MHz chan- 
nels that belonged to the Citizens Radio of 
old, now called the General Mobile Radio 
Service (GMRS). and proposed to estab- 
lish in those channels a CB Consumer 
Radio Service based on low- power hand- 
held radios. 

Tli at proposal was greeted with as- 
tonishment by a large user of the GMRS 
channels, REACT, the national associa- 
tion of volunteer emergency-communica- 
tions teams, and by many non -affiliated 
personal-radio users and community- 



watch groups. Those users have operated 
GMRS repeater systems for years and did 
not take kindly to the FCC's recommen- 
dation that the Consumer Radio Service 
be limited to short-range, unlicensed 
walkie-talkies. GMRS licensees are busy 
with a campaign to alert their congres- 




THIS MIDLAND 70-526 mobile UHF transceiver 
is designed tor GMRS use. 

sional representatives to the take-away 
that the Consumer Radio Service seems to 
represent. The FCC maintains that it's 
keeping an open mind on the subject and 
won't do anything with the GMRS chan- 
nels until all of the formal comments are 
received (the deadline for that was this 



past June 30) and it has had a chance to 
analyze them. 

Flexible radio service 

So far, there is still one part of the 800- 
MHz band that remains unallocated. 
We've looked at some of the radio ser- 
vices proposed for this band, including 
one (PRCS) that appears to have been 
ruled out. The lucky radio service or ser- 
vices that receive an 800-MHz allocation 
will undoubtedly start a new industry or 
enhance an existing one, depending on 
how the allocations are made. Has the 
FCC given any indication as to what it 
will do? 

Several Commissioners and staff mem- 
bers have indicated that they would like to 
try a totally different approach to spec- 
trum allocation. Instead of weighing the 
arguments presented by petitioners and 
granting the requests they determine are 
most in the public interest, the FCC is 
examining the possibility of throwing the 
remaining portion of the 800-MHz band 
wide-open for any lawful use by selected 
licensees. 

That would be accomplished by a lot- 
tery or auction process to award a limited 
number of nationwide licenses to parties 
who in turn would decide for themselves 
which service — mobile radio, cellular 
telephone, paging, satellite, video, etc. — 
would be most profitable. They could then 
implement their spectrum allocation. 



That would relieve the commission of the 
difficult task of deciding which proposed 
communication services are most bene- 
ficial to the public, and would leave the 
future of the spectrum in the hands of the 
marketplace. 

Thai proposal, known generally as the 
Flexible Allocation or Flexible Radio Ser- 
vice, has produced heated debate from 
within and outside the FCC. The ap- 
proach could result in the necessity for 
two-way radio users to buy their channels 
instead of receiving them "free" with an 
FCC license. 

Such a Flexible Radio Service could, 
theoretically at least, bring new commu- 
nications technologies to market faster 
because detailed FCC approval at every 
step along the way would not be needed. 
Proponents of flexible allocation say it is 
our last chance to try something inno- 
vative with the radio spectrum. Oppo- 
nents of the controversial proposal say it is 
wrong to conduct economic experiments 
with precious frequencies needed for pub- 
lic services. 

Millions, if not billions of dollars hang 
in the balance of those critical decisions 
about how the radio spectrum should best 
be allocated. The UHF band — par- 
ticularly 800 MHz — will be the cause of 
quite a few interesting battles over the 
future of communications. Who do you 
believe should win the "Spectrum 
Wars?" R-E 



FROM DC TO MICROWAVE 



continued from page 48 



SIGNAL FROM 

MMUNtCATIONS 
SATELLITE 



that property is what makes things like 
radar (which is an acronym for RAd\o 
Detection And flanging), used for tracking 
airplanes as well as speeding motorists, 
possible. 

Microwave is used for communications 
in areas where it is impractical to lay or 
string cables. Microwave receivers and 
transmitters located atop high towers in 
rural areas, or on tall buildings in cities, 
relay communications over spans of doz- 
ens of miles at a time. Much transconti- 
nental voice and data communications, 
once handled by cable, is now accom- 
plished via microwave links. 

The frequencies used by communica- 
tions satellites are also located in the SHF 
part of the spectrum. Because, with their 
relatively short wavelengths, microwaves 
act like fight, they can be treated like 
light. The familiar satellite dish (see Frg. 
3) is actually the radio equivalent of a 
reflecting telescope. The purpose of the 
dish in a receiving installation is to collect 
the microwave signals coming from a sat- 
ellite transponder and focus them on an 
antenna (called a probe) located at the 
dish's focal point (within a feedhom). 
Similarly, in a transmitting set-up, the 




FIG. 3— BECAUSE THEV HAVE PROPERTIES 
similar to those of light, microwave signals can 
be collected and focused on an antenna element 
by a metal Ic surfaced reflector. That property is 
the basis of the satellite dish. The satellite dish 
Is the radio equivalent of the optical reflecting 
telescope. 

dish is used to concentrate microwave sig- 
nals into a tight beam. Satellite-TV ac- 
tivity takes place between 3.4 and 4.2 
gigahertz (the C-band) and between 11.7 
and 12.7 gigahertz (the Ku-band — pro- 
nounced "cue-band"). 

There is some concern over the effects 
of microwave radiation on the human 



body. Just as a microwave oven can induce 
heating in organic (and metallic) mate- 
rials by stimulating molecular motion (the 
faster molecules or atoms move, the hotter 
they become), any microwave source can 
do the same. There have been reports that 
microwave technicians, particularly those 
working with high power levels, have suf- 
fered higher than normal rates of certain 
disorders such as cataracts. To most of us 
microwaves pose no health threat but nev- 
ertheless, like anything that is potentially 
dangerous, they should be treated with 
care and respect. 

And beyond 

Above the SHF band is the EHF (Ex- 
tremely Wigh Frequency) region. Fre- 
quencies there are most conveniently 
specified in terahertz — thousands of bil- 
lions of cycles per second. Wavelengths 
in the EHF region arc only in the milli- 
meter range (for reference, a dime is a 
little less than a millimeter thick). At the 
top end of the range, the frequencies 
border on those of infrared light. While 
little use is made of these frequencies at 
present, they are beginning to be ex- 
ploited for communications in space. It is 
safe to expect that use of those frequencies 
will ga>w as our exploration of space con- 
tinues, and as the frequencies below be- 
come occupied. R-E 




TV SIGNAL 
DESCRAMBLING 



More on PLL's and bow they can be 
used in practical descrambling circuits. 



WILLIAM SHEETS and RUDOLF F. GRAF 



Part 4 



LAST TIME, WE 

looked at some 
practical descrambling circuits. At the 
heart of several of those circuits was the 
fhase-Locked Loop (PLL). This month, 
we'll begin by looking more closely at 
PLL's, and how they can be used to de- 
scramble various types of signals. 

Phase-locked loops 

Thanks, in part, to the widespread pop- 
ularity of FM stereo radio, a number of 
singie-IC PLL FM-stereo demodulators 
have been developed. Generally those de- 
vices contain an input amplifier, a phase 
detector, a VCO (Voltage Controlled Os- 
cillator), some form of lock detector for 
audio muting or stereo lamp switching, a 
decoder matrix, and a voltage regulator 
that allows the unit to operate from a wide 
variety of supply voltages. Some of those 
devices require little in the way of external 
components, including hard-to-lind coils, 
to operate. 

PLL's are ideal for regenerating the 15-, 
31-,40-,or62-kHzsubcarriersused in the 
gated-sync, sinewave, or SSAVI systems 
that we have discussed previously. Where 
appropriate, PLL's can also be used to 
demodulate hidden audio subcarriers, 
thus doing two jobs for the price of one. 
Further, because PLL's are mass pro- 
duced, they are easily obtained and inex- 
pensive. 

Figure 1 is a block diagram of a typical 
PLL. Basically, a PLL operates by com- 
paring the frequency of an input signal 
with that of a signal generated by an on- 
board VCO. The VCO is set up to shift 
frequency such that its output frequency 
and that of the PLL's input signal are iden- 
tical. Both signals are applied to a phase 
detector, which is where the actual com- 
parison takes place. (In some instances 
the VCO is set up to operate at a multiple 
of the input frequency range. In PLL's 
where that is done, a frequency divider is 
inserted in the loop between the VCO and 



Over the next few months, Radio- 
Electronics will be presenting a se- 
ries of articles describing the tech- 
niques used by pay-TV and cable 
companies to scramble their signals. 
While specific circuits for specific 
scrambling systems will be discussed, 
they are presented for informational 
and experimental purposes only. 
Therefore, parts lists, parts suppliers, 
and additional technical support will 
not be available for those circuits. 

the phase detector.) If the frequencies of 
the input and the VCO signals differ, the 
phase detector produces an AC signal. 
Otherwise, a DC voltage that is propor- 
tional to the phase difference between the 
two signals is produced. Thus, once the 
PLL is "locked," that is, once the input 
and VCO frequencies match, only a phase 
error exists between the two signals. The 
frequencies of the i nput and output signals 
are equal . The output of the phase detector 
is fed to an amplifier/integrator. That 
stage produces the control voltage for the 
VCO. 




recovering only one mono channel. 
Therefore, only one of the audio outputs is 
used. However, we do need to recover the 
pilot signal. In FM-stereo systems, the 
pilot is used only to indicate the presence 
of a stereo signal. But in some scrambling 
systems, such as gated pulse, that signal is 
needed for sync regeneration. For other 
scrambling systems, the pilot signal could 
be used to switch in the decoder automat- 
ically at the appropriate time. 

The PLL used in the circuit of Fig. 2 is 
designed for I9/38-kHz operation. If 
needed, we feel that the LMI800 could be 
made to operate at frequencies up to 100 
kHz because it's fabricated using tran- 
sistors that inherently can operate to sev- 
eral megahertz. However, we have not 















— «-0 OUTPUT 

T 


PHASE 
DETECTOR 




AMPLIFIER 
& INTEGRATOR 




VCO 


FREQ 
IREFEBENCE) 


ERROR 


VCO 


. 


■ 


SIGNAL 




CONTROL 
VOLTAGE 




-»N 
(OPTIONAL! 






FEEDBACK 
innp 

















FIG. 1— A PLL IS AT THE HEART of many descrambling circuits. A block diagram of that device, 
commonly available In IC form, Is shown here. 



A circuit that can be used for subcarrier 
regeneration is shown in Fig. 2: the heart 
of the circuit is an LMI800 PLL stereo- 
demodulator IC. The circuit is very sim- 
ilar to the one that would be used for FM- 
stereo detection. With subcarrier-re- 
generation circuits, we do not have to wor- 
ry about stereo separation, since we are 



been able to confirm that. 

In any event, the most commonly used 
subcarrier frequencies are within the 
range of the LMI800. In the gated-pulse 
system, where the audio is usually en- 
crypted on a 15-kHz subcarrier, the circuit 
of Fig. 2 could be used both to recover the 
subcarrier and to decode the audio. 



54 




C5 
,0027 



<»T_!2 
.003 g 



IC1 
LM180Q 



R6 
3.9K 



LED l 




^o AUDIO OUTPUT 
C9 (IF REQUIRED! 
,002 

PtLOT 
ILlf-O OUTPUT TO 
lx SYNC CIRCUITS 



(ISfcHzl 



CI 

AUDIO Mf 
INPUT O— ft-* 
115kHz) 

Rl 
10K 

FIG. 2— THOUGH DESIGNED FOR FM-STEREO DEMODULATION, the LM1800 PLLcan be used to good 
advantage in descrambling systems. Here that IC is used to regenerate a hidden subcarrier. 



■ + 12V 



INPUT 
FROM 

VIDEO 
DETECTOR 



4.5 MHz 
FILTER 



4.5MHz 
FILTER 



TUNING, LEVEL, 

i PHASE ADJUSTMENT 




-w- 



4.5MHz 
AMP 



DETECTOR < J- 



ACTIVE 

FILTER 

& AMPLIFIER 



15 KHz 

FILTERED 

SINEWAVE 

OUTPUT 



FIG. 3 — THIS BLOCK DIAGRAM shows the system used to recover the descrambling sinewave 
required by a sinewave decoder. 



III the sinewave system, the audio is 
placed on a 62.5-kHz subcarrier. For that 
scrambling system, the circuit of Fig. 2 
would be used only for recovering the 
audio. Note that some modifications to 
the highpass filter at pin 1 anil the VCO's 
frequency-control circuit at pin 15 would 
be necessary to accommodate the dif- 



ferent frequency. The circuit as shown is 
designed for 15 -kHz operation. In the 
highpass filter, CI and C2 should both be 
changed to 470-pF units. In the VCO con- 
trol circuit, C7 should be replaced with a 
100-pF unit. Alternately, R3 and R4 could 
be replaced with 6.8K and 5K units, re- 
spectively. You may need to modify the 



PLL loop filter and the threshold filter. 

A worthwhile experiment would be to 
set up the circuit on a breadboard and to 
check out its operation using an audio or 
function generator to supply the needed 
input signal. 

Sinewave decoding 

The procedure used to recover the sync 
in the sinewave scrambling system differs 
somewhat. In the sinewave system, the 
synchronized 15-kHz sinewave is encoded 
on the 4.5-MHz sound subcarrier. In a 
conventional TV-.sound Iimiter, that AM 
component is stripped away. Therefore it 
does not appear at the output of the sound 
detector and we must obtain that signal at 
a different point in the signal processing 
trail. 

Figure 3 shows a block diagram of a 
circuit that could be used to recover the 
decoding sinewave. The 4.5-MHz sound 
subcarrier is taken from the video detec- 
tor. It could also be taken from the TV 
set's sound/sync detector, if the set has 
one (not all do), or. if possible, from the 
sound IF before limiting has taken place. 

After the 4. 5- MHz sound subcarrier 
has been obtained, it is amplified and then 
fed to an envelope -detector stage. The 
output of the detector contains the low- 
level 15-kHz signal (modulation percen- 
tages of 5 to 15 are typical), as well as 
unwanted components such as induced 
AM audio from the sound channel. 

The unwanted components are removed 
by a high-Q active filter. In that stage the 
signal is also amplified and its phase ad- 
justed so that it differs from the encoding 
signal by 180°. Finally, any distortion due 
to non-linearity, harnionics, etc. is re- 
moved: the recovered signal must match 
the encoding one exactly, except for the 
phase difference, or incomplete cancella- 
tion will take place. The result would be 
ripples, shading, etc. in the picture. 

It is possible to distort the recovered 
signal deliberately to compensate for non- 



J- 22K> 



4.5MHz 

INPUT 
O- 



i 



FL1 
4.5MHz CERAMIC 
MUflATA FILTER 

1 



C 



X 



R3 
4.7K 



C2 
390pF 

Ql 
2N3563 i 

m 



Ll< 
321 nH I 



-12V 



R4 

470! 2 



^rV*- 
R5 

• 47011 

C4 
.01 

-M- 



R6 

2K 

TUNE 

XtJ 



i IUN 

-J ^-*AA 



-VSrV 



4.S 

MHz 

AMP S DETECTOR 



1 
I 



01 , 
IN270 



R7 
IK 
-VA- 
CS 
.001 



I 



RS 
22011 

R9 
2.2K 

C6 
ISjiF 
„1QV 



ca 

470pF 

•_ 5 % 
MICA 



C7 
470 pF 

± 5% 
MICA 



Ria 

100K 



- 100Ki k m 




■12V 



15KH? 

ACTIVE 
FILTER 




CO 

m 

Tl 
H 

m 

2 
m 



FIG. A — HERE THE BLOCK DIAGRAM OF Fig. 3 is translated into a practical circuit. Any op-amp 
designed for audio work may be used for 1C1. 



(O 



55 



to 
o 

2 

o 

£E 

F- 
O 



o 

Q 
< 

rx 



linearity elsewhere in the decoder, such as 
in the modulator. However the best de- 
coders are the ones that are well designed 
(i.e. linear) in the first place. Generally, if 
the si newavc -recovery circuit requires 
tweaking or tailoring to match the balance 
of the decoder, it is an indication of a 
poorly designed system. A circuit that is 
well engineered should work the first 
time, and not require any critical adjust- 
ments or adjustment techniques. For the 
most part, the circuits that we are present- 
ing in this series meet that criteria. If the 
circuit is unstable, or requires critical ad- 
justment, it is an indication that some- 
thing is wrong. 

Now let's translate our block diagram 
into a practical circuit. One representative 
circuit is shown in Fig. 4. In that relatively 
simple circuit, the 4.5-MHz signal is 
taken from the TV sound system before 
limiting. It is passed through a 4.5-MHz 
ceramic filter to eliminate any "junk" 
(unwanted components), and then ampli- 
fied by Ql, an NPN transistor that has a 
gain of 25 to 30 dB. A 4.5-MHz tuned 
circuit in the collector circuit of Ql serves 
as a load, across which the 4.5- MHz out- 
put-signal is developed. The signal is then 
diode detected and fed to the active-filter 
stage. The filter has a nominal gain of 40 
dB and is tuned to 15 kHz, tn thai stage the 
phase shift of the signal is adjusted as 
previously described. That adjustment is 
made by varying the setting of R6. The 
response of the active filter is much like 
that of a tuned LC circuit. While a 741 is 
specified for 1CI, almost any op-amp de- 
signed for AF operation is suitable. 
Among the other possible choices are an 
RC4558. an LM1458. or a 747. The out- 
put of the circuit is taken from RI3. the 
10K LEVEL potentiometer. 

During operation, the circuit should be 
checked with a scope for linearity. To be 
conservative, the 15-kHz signal seen at 
the output of the op amp should never 
exceed about one half the supply voltage. 
For example, in the circuit of Fig. 4, 
which is designed to use a 12-volt supply, 
that voltage should not exceed 6- volts p-p. 
The level of the 4. 5- MHz input signal will 
be between about 30 and 100 millivolts, 
depending on the modulation level. Note 
that levels higher than that could cause 
limiting in either the amp or the active 
filter stages. That will result in a distorted 
1 5 -kHz sinewave at the output and in- 
complete descrambling. 

The circuit shown in Fig. 4 can be com- 
bined with the circuit shown in Fig. 7 of 
Part 3 of this series (see the August, 1986 
issue of Radio-Electronics) to form a 
functional sinewave decoder. However, 
installing the decoder would require at 
least some familiarity with how a TV set 
works, as several internal connections are 
required. Among other things, you must 
know where to tap off the required inputs, 
where to feed the descrambled output. 



V 




r 

CABLE 

SYSTEM 

INPUT 

(SCRAMBLED 

SIGNALS) 



TUNER 
(VHF-UHF) 

1 



IF AMP 
145 MHzl 



DETECTOR 



AFT/ 

AGC 

SYSTEM 



(SCRAMB 
VIDEO 



SOUND 
14.5 MUe) 



DE- 
SCRAMBLER 
CIRCUITRY 
(DECODING TAKES 
PLACE HERE) 




RECOVERED AUDIO SUBCARRIER 



RECOVERED VIDEO 



VIDEO 
AMPLIFIER 



NORMAL VIDEO 



SOUND 
DETECTOR 

IIF REQUIRED! 



IM0RMAL AUDIO 



VIDEO & AUDIO 
MODULATOR 



CH3 OR CH4 

OUTPUT 

(UNSCRAMBLED) 

O 



FfG. 5— TO AVOID COMPLICATED INSTALLATIONS, the decoder can be combined with a TV front-end 
to form a converter-desc ram bier. The output of that circuit can be fed directly to the antenna input on a 
TV set. 




FIG. 6 — A SIMPLE RF MODULATOR, tf you wish, a modulator could atso be obtained trom a discarded 
videogame or computer. 



and where to obtain the required supply 
voltages. For some, that would present 
little problem. But many others do not 
have the required expertise. Further, the 
growing use of IC's in TV sets presents a 
problem. In many IC-intensive TV sets, 
the required tap-off points may be con- 
tained within an 1C, making them inac- 
cessible. In that case, it would he virtually 
impossible to connect our decoder. 
The solution to those problems is to 



design a decoder that essentially contains 
a complete TV-set "front-end." The de- 
coder would then contain a tuner. IF amp, 
video and audio detectors, and an RF 
modulator. The output of the decoder 
could then be fed to a user's TV set via the 
antenna input. 

Such a unit would most properly be 
called a converter-descrambler. Its block 
diagram is shown in Fig. 5. In it, signals 
from an antenna or cable system are fed to 



56 



INPUT 



C7 

470pF 



4 C15* f- 



L6' 




•SEE TEXT 



Ch- 



lrJ914B 

— W- 



R5 

nn 

R4 

2.2K 



C16 
470pF 

-K- 



<'27!i 



[N914B 




C17 

470pF 

— J| ©OUTPUT 






C185 

470pF 



Ban 



■~C^H 



R1 

471J 
-VA- 



■II -15V 



FIG. 7— IN THE OUTBAND SYSTEM, used only on cable-TV systems, the sync Is hidden on an unused 
frequency, outside of the channel itself. Therefore, a decoder, like the one shown here, must have some 
way to "tune In" that out-of-channel sync signal. 



a tuner and on to a 45-MHz IK amp: 45 
MHz is a standard TV IF frequency. From 
the amp, the signal is fed to standard TV 
sound and video detectors. "The outputs 
from the detectors are scrambled video 
and the 4.5-MHz audio subcarrier. Those 
are the signals that the descrambler needs 
to do its job. The outputs of the de- 
scrambler stage are a normal video signal 
and either a normal audio signal or a re- 
covered audio subcarrier. depending on 
the scrambling system. In the latter case, 
the subcarrier is fed to a second sound 
detector to recover a normal audio signal . 
The audio and video could be fed directly 
to a set with audio/ video inputs, but a 
more "universal" approach would be to 
feed those signals to an RF modulator set 
up to output on cither Channel 3 or 4. A 
standard RF modulator circuit is shown in 
Fig. 6, Alternately. RF modulators are 
available commercially or can be salvaged 
from a discarded videogame orcomputer. 

The SSAVI system 

As previously discussed. SSAVI (Sup- 
pressed Sync And Video /aversion) is one 
of the more sophisticated of the scram- 
bling techniques, in that system, four 
modes of operation are possible. Those 



are: suppressed sync and inverted video, 
suppressed sync and normal video, nor- 
mal sync and inverted video, and normal 
sync and normal video (unscrambled). 
The system has the capability to switch 
between any of the four modes on a frame- 
to- frame basis. Therefore the scrambling 
method can change as often as 60 times- 
per-second. if desired. The sound is strip- 
ped from the audio subcarrier and placed 
on another subcarrier located at 39,335 
kHz (2.5 times the horizontal frequency). 

Further complicating the task of de- 
scrambling is the fact that no reference 
signal is sent with the scrambled picture. 
The decoder must provide its own refer- 
ence. Also, the decoder must be able to 
detect whether or not the video is inver- 
ted. Note that the syne signal is never 
inverted, so the decoder circuitry must 
only invert the video portion of the signal, 
when required. The sync signal may, 
however, be suppressed. 

How does a decoder regenerate the 
sync and detect when the video is inver- 
ted? In the SSAVI system, the first 26 
lines of the picture are sent with normal 
sync pulses. A PLL can lock onto that 
information and supply the missing infor- 
mation for the rest of the frame. The re- 



generated sync is used to restore normal 
syne, which in turn is used as a reference. 
The leading edge of the vertical sync pulse 
is used as a reference from which all oper- 
ations are timed. During the 20th line, 
which is picked out by the decoder by 
using a counter circuit, information is sent 
as to whether the video in the frame is 
inverted or normal. 

As you can see, the SSAVI decoder is 
called on to perform a number of tasks. 
Because of that, the circuitry is rather 
extensive. Fortunately, it is also rather 
straightforward. We will look at the de- 
tails in the next installment in this scries. 

Note that the typical SSAVI de- 
scrambler contains much circuitry that is 
not involved in the descrambling process. 
Thai includes anti -theft circuitry, as well 
as circuitry that allows for two or more 
tiers of premium programming. As such 
circuits play no part in the descrambling 
process, they will not be discussed. 

Outband descramblers 

Before we wrap up for this month, let's 
look at a system that is used in many cable 
systems. Called the outband system, in it 
the sync signal is placed on a subcarrier. 
but the subcarrier frequency is not within 
the channel. Instead, it is within an un- 
used cable channel. The frequencies most 
often used are somewhere around 50 MHz 
(below broadcast Channel 2) or between 
90 and 120 MHz (those frequencies fall in 
the FM-broadcast and aviation bands). 

As described in a previous installment, 
to recover the sync the decoder requires a 
circuit that can "tune in" the out-of-chan- 
nel carrier. A typical outband decoder is 
shown in Fig. 7. In that circuit, the com- 
posite cable signal is split two ways. The 
sync frequency is passed by an appropri- 
ately tuned input filter and fed to a video 
IF-amp stage. A trap, set up to be resonant 
at She sync-carrier frequency, prevents the 
sync signal from appearing at the output. 
From the IF amp. the sync signal is fed to a 
video detector. The output of the video 
detector (pin 5, 1C2), which consists sole- 
ly of sync pulses, drives a differential 
amplifier. The differential amp drives a 
voltage-controlled attenuator. When a 
sync pulse is not present, the output of the 
video detector goes negative and the cur- 
rent from the differential amp reverse 
biases Dl and forward biases D2. That 
"inserts" the attenuator in the circuit. 
When a sync pulse is present, the output 
of the detector goes positive. Then, Dl is 
forward biased while D2 is reverse biased. 
Tli at removes the attenuator from the cir- 
cuit. 

Note that values for the components in m 
the traps and filters have not been spec- 3j 
iticd. That's because those values can vary m 
widely, depending on the frequency of the 6j 
sync channel. In a future installment we x 
will present a more detailed version of the £ 
circuit. R-E m 



57 




How to 




Design OSCILLATOR Circuits 



JOSEPH J. CARR 



Our series continues with a discussion of RC oscillators, ways of generating sinewaves from 
other waveforms, and other topics. 



Part 3 



IN THE PAST TWO IN- 

stallments of this se- 
ries wc discussed relaxation oscillators 
and feedback oscillators built from LC 
tank circuits. This time we'll look at RC 
oscillators. Some of our example circuits 
are built from FET's and bipolar tran- 
sistors; others are built from operational 
amplifiers. But whatever components 
they're built from, all our circuits have 
one thing in common: The frequency at 
which a given circuit oscillates is deter- 
mined by one or more RC time constants 
in the circuit. 

The phase-shift oscillator 

As we learned in a previous install- 
ment, a feedback oscillator works by 
feeding a portion of a circuit's output sig- 
nal back to its input. The signal that is fed 
back must be applied in phase with the 
input signal. Since we usually use an in- 
verting amplifier (which provides 180 de- 
grees of phase shift) as the active element 
of a feedback oscillator, wc must obtain an 
additional 180 degrees of phase shift from 
other circuit elements. In the three-leg RC 
phase-shift oscillator shown in Fig. 1, 
each leg provides 60 degrees of phase 
shift, for a total of 180 degrees. An op- 
amp version of the phase-shift oscillator is 
shown in Fig. 2. Both circuits produce a 
sinewave output signal. 



X 



C4 



R4. 



M ( f K T K T Qg 



-»- + V 



;ER1 ;:R2 ;:R3 R5 



C5 

OUTPUT 



G1 = C2 = C3 
R1 = R2=R3 

FIG. 1— EACH RC PAIR PROVIDES 60" of phase 
shift for a total of 180 ; that phase shift com- 
bines with the 180° provided by the FET for a 
total of 360°. 




FIG. 2— A PHASE-SHIFT OSCILLATOR can also 
be built from an op-amp. R F must be at least 30 
times the value of R1 for the circuit to oscillate. 



The frequency at which either circuit 
will oscillate is determined by the values 
of R1-R3 and Cl-GS; to keep the mathe- 
matics simple, we usually give each re- 
sistor the same value; likewise with the 
capacitors. In Fig. 1, the other resistors 
(R4 and R5) serve to bias the FET, and 
capacitor C5 provides DC isolation. We'll 
discuss the function of the op-amp cir- 
cuit's R h . below; first let's sec how to cal- 
culate oscillating frequency. 

Assuming that R1 = R2 = R3 and that 
ei=G2=C3, then 



f 



1 



2n V6RC 



In that equation, R = Rl and C = Cl. If 
resistance is specified in ohms and capaci- 
tance in farads, then frequency will be 
given in hertz. 

When the constant terms in that equa- 
tion are combined, we can rewrite the 
equation as follows; 

f = 1/(15.4 RC) 



or as 



0.408 / (2ji RC) 



When designing an oscillator we usually 
need to find a resistor/capacitor combina- 
tion that will produce a desired frequency, 
so another form of the equation can also 
be useful. Since there are fewer standard 



58 



capacitor values, wc tend to select one and 
then plug it and the desired operating fre- 
quency into the equation to find the clos- 
est resistor value which will produce that 
frequency. So we rearrange the equation 
as follows: 

R = 0.408/(2,-1: 1C) 

Let's take an example: Find the resistance 
required to produce a 1000-Hz oscillator 
with a 0.0 1 -|iF capacitor. 
0.408 
2 x 3.14 x 1000 x .01 x 10-« 
R = 0.408/(6.28 x 10" 5 ) 
R = 6497 ohms 

In any feedback oscillator we must ensure 
that the closed-loop gain is unity or more. 
Trie closed-loop gain of the circuit in Fig. 
2 is the ratio R F /R. Analysis reveals that 
the loss in the feedback circuit is Vi9, so 
circuit gain must be greater than 29 in 
order to ensure oscillation. So R F should 
be at least 30 times the value of R . For the 
1000-Hz oscillator discussed previously, 
R F should be 30 x 6497 = 194,910 
ohms. You could use a 200K resistor, 
which is the closest standard value. 

BASIC program 

To ease the tedium of calculating the 
values of the frequency-determining com- 
ponents in a phase-shift oscillator, we 
wrote the simple BASIC program shown 
in Listing I. The program was written in 
the dialect of BASIC that runs on the 
IBM-PC, but it will run on many ma- 
chines unmodified, and it should be easy 
to translate into another dialect. 

The program calculates component val- 
ues for either three-leg phase-shift os- 
cillator presented above; in addition, it 
will calculate minimum and maximum re- 
sistor values for a variable- frequency os- 
cillator. To build a variable- frequency 
oscillator, you would have to use a triple- 
gang potentiometer or a triple-pole switch 
to select appropriate resistors. 

When you run the program, it asks 
whether you want to calculate values for a 
fixed- or a variable-frequency oscillator. 
You must then type in the frequency (or 
the frequency range) you need. Then the 
program will request the value of the tim- 
ing capacitor. Last, it calculates and dis- 
plays the resistance (or range of 
resistance) that will be required . 

It is possible to vary the frequency of a 
variable-frequency phase -shift oscillator 
over a range greater than 10:1 using just 
resistors, but it is impractical to do so. 
Circuit considerations aside, it becomes 
difficult to adjust the frequency accu- 
rately. Hence the program prints a warn- 
ing if you enter high and low frequencies 
that are in a ratio greater than 10: 1 . If you 



LISTING 1 


IB GOSUB 920 


650 


RL = 1/(15, 391*C*FL> 


20 PRINT "This program calculates 


660 


RL = INTtRL) 


30 PRINT "the component valties 


670 


HH = 1/(15. 391*C*FH> 


40 PRINT "for an PC phase-shift 


680 


RH - INT(RH) 


50 PRINT "oscillator. 


690 


R4 = 30*RH 


60 PRINT 


700 


R4 = INT[R4) 


70 PRINT 


710 C - C*10"6 


80 GOSUB 960 


720 


GOSUB 880 


90 GOSUB 920 


730 


PRINT "Component Values for 


100 PRINT "CHOOSE one: 


740 


PRINT "Variable Frequency 


110 PRINT 


750 


PRINT "Oscillator 


120 PRINT "1. Fixed oscillator 


760 


PRINT 


130 PRINT "2. Variable oscillator 


770 


PRINT "Frequency Range:"; 


140 PRINT 


780 


PRINT FL;" to ";FH;" Hz 


150 INPUT "SELECTION?", A 


793 


PRINT "Capacitors C1=C2=C3="; 


160 IF A > 2, THEN GOTO 100 


800 


PRINT C;" uF 


170 ON ft GOTO 180, 480 


810 


PRINT "Resistor Range"; 


160 GOSUB 880 


820 


PRINT RH;" to ";RL;" Ohms 


190 PRINT "Fixed Frequency 


830 


PRINT "Feedback Resistor R4: n 


20O PRINT "option selected 


840 


PRINT R4;" Ohms 


210 PRINT 


850 


GOSUB 880 


220 INPUT "Frequency in Hz?",F 


860 


GOSUB 960 


230 PRINT 


870 


GOTO 1150 


240 PRINT 


880 


FOR I = 1 TO 5 


250 INPUT "Capacitance in uF",C 


890 


PRINT 


260 C = C/(10"6) 


900 


NEXT I 


270 R = 1/(15. 391*C*F) 


910 


RETURN 


230 R = INT(R) 


920 


FOR I = 1 TO 30 


290 R4 = 30 *R 


930 


PRINT 


300 C - C*10"6 


940 


NE)CT I 


310 GOSUB 880 


950 


RETURN 


320 R4 - INT(R4) 


960 


PRINT "press any key . . ."; 


330 PRINT "Component values for 


970 AS-INKEYS: IF ftS="" THEN 970 


340 PRINT "fixed frequency version 


980 


RETURN 


350 PRINT 


990 


GOSUB 880 


368 PRINT "Operating Frequency:"; 


1000 


PRINT "Frequency range is 


370 PRINT F;" Hz 


1010 


PRINT "greater than 10:1. 


380 PRINT "Capacitors C1=C2=C3="; 


1020 


PRINT "It would be better 


390 PRINT C;" uF 


1030 


PRINT "to break the range 


400 PRINT "Resistors R1=R2=R3="; 


1040 PRINT "into two bands. 


410 PRINT R;" Ohms 


1050 


PRINT " You can: 


420 PRINT "Feedback Resistor R4="; 


1060 


PRINT 


430 PRINT R4;" Ohms 


1070 


PRINT "1. Continue anyway 


440 PRINT 


1080 


PRINT " or 


450 PRINT 


1090 


PRINT "2. Do something else 


460 GOSUB 960 


1100 


PRINT 


470 GOTO 1150 


1110 


INPUT "SELECTION?" ,W 


480 GOSUB 920 


1128 


IF W > 2, THEN GOTO 990 


490 PRINT "Variable Frequency 


1138 


ON W GOTO 1140,90 


500 print "option Selected 


1148 


RETURN 


510 PRINT 


1158 


PRINT 


520 PRINT "Set upper and lower 


1168 


PRINT "What's Your Pleasure? 


530 PRINT "frequency limits 


1178 


1 PRINT 


540 PRINT 


1188 


PRINT "1. Repeat 


550 INPUT "Lower Limit in Hz?",FL 


1198 


I PRINT "2. Start over 


560 PRINT 


1208 


i PRINT "3. All done 


570 INPUT "Upper Limit in Hz?",FH 


1218 


I PRINT 


580 PRINT 


1228 


1 INPUT L 


590 IF FH > 11*FL THEN GOSUB 990 


1236 


1 IF L > 3, THEN GOTO 1150 


600 GOSUB 880 


1248 


( ON L GOTO 170,100,1250 


610 PRINT "Value of capacitor: 


1258 


1 GOSUB 920 


620 PRINT 


1268 


i PRINT "PROGRAM ENDED 


630 INPUT "Capacitance in uF?",C 


127« 


1 END 


640 C = C/10'6 







really need a wide- range variable-fre- 
quency oscillator, be patient; we'll dis- 
cuss a technique for designing one below. 

Wien-bridge oscillator 

Another common RC oscillator is 
called a Wien bridge; it is a bridge circuit 
that resembles a Wheat stone bridge. As 
you can see in Fig. 3, two arms of the 
Wien bridge are purely resistive, and the 
other two are RC networks. One of the RC 
networks is a series circuit, and the other 
is a parallel circuit. The feedback loop is 



degenerative (hence stable) at all frequen- 
cies other than the oscillating frequency, 
which is given by: 

1 



f = 



2rt VR3 x R4 x C1 x C2 



If R3 = R4 and C1=C2, then that equa- 
tion can be simplified as follows: 

f = 1/(2nR3xC1) 

Like the phase-shift oscillator, the Wien- 
bridge oscillator produces a sinewave out- 
put, but its amplitude tends to be somc- 



m 

Tl 

H 

m 

CD 

m 

CO 

CO 



59 



CO 

g 

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O 
cr 

h- 
o 

LU 



o 

Q 
< 




FIG. 3— A WIEN-BRIDGE OSCILLATOR resem- 
bles a Wheatstone bridge. Amplitude stability 
can be improved by substituting a low-current 
lamp for H2. 



-K T- 

i 



)J 1 -v* — +v 



C2 



R2 " R3 

k »M- — f — Wy — -+ — O OUTPUT 



;C3 



Q1 



^ 



R4 



Rl = RZ - R3 
CI = C2 - C3 



FIG. 4— TWIN-TEE OSCILLATOR is composed of 
two "T" shaped networks. One has series ca- 
pacitors and a shunt resistor; (he other has se- 
ries resistors and a shunt capacitor. 



-VW 




OOUTPUT 



FIG. 5— THIS BRIDGED-TEE OSCILLATOR uses 
an incandescent lamp to increase amplitude 
stability of the output signal. 




FIG. 6 — ANOTHER BRIDGED-TEE OS- 
CILLATOR; in both this circuit and the one 
shown in Fig. 5, the bridging component Is the 
"opposite" of the T's series element. 



SQUAREWAVE 
GENERATOR 


— ^ 


BANDPASS/ 

LOWPASS 

FILTER 



-o OUTPUT 



FIG. 7— LOWPASS OR BANDPASS FILTERS can 
clean up a squarewave source and provide a 
pure sinewave output. 



amplitude of a squarewave oscillator is 
inherently stable because it operates in a 
saturating mode wherein the output 
swings between two well-defined volt- 
ages. Therefore some designers prefer to 
use a squarewave or a triangle wave gener- 
ator as the basic oscillator, and then shape 
its output into a sinewave. 







Fl 


F2-F1 








—6 OUTPUT 




VARIABLE- 
FREQUENCY 
OSCILLATOR 
80 kHz -100k Hi 




amplifierJ> 


( MIXER j 
F2 T^ 






1 
LOWPASS 
FILTER 










* 






FIXED- 
FREQUENCY 
OSCILUTOR 

100kHz 





















FIG. 8— A WIDE-RANGING OSCILLATOR can be bu 
Their outputs are mixed, the difference is taken 
output. 

what unstable, especially in a variable- 
frequency oscillator. It is possible to re- 
duce that instability by replacing R2 with 
a low-current (40-mA) incandescent 
lamp. "Dial type of lamp has a non-linear 
voltage-current characteristic that helps 
stabilize the output amplitude and prevent 
the amplifier from saturating. The lamp 
should be operated below incandescence. 

Twin- and bridged-tee oscillators 

There are several other types of sine- 
wave oscillators based on RC networks. 
The circuit in Fig. 4 is called a twin-tee 
oscillator because its feedback network 
consists of two T-shaped networks. Note 
that those networks are, in a sense, op- 
posites. One uses series resistors and a 
shunt capacitor, and the other uses series 
capacitors and a shunt resistor. If 
R1 = R2 = R3 andCl=C2 = C3, the cir- 
cuit's oscillating frequency is about: 

f=V(2n RC) 

A more useful form of that equation is: 

R = 1/(2,1 /C) 

For example, when each capacitor has a 
value of 0.0 1 u,F, the resistance required 
for a 500-Hz twin-tee oscillator is: 

R = 1/(2 x 3.14 x 500 x 0.01 x 10~«) 

R = 1/(3.14 x 10-5) 

R = 31,831 ohms 

Another type of "tee" oscillator is called 
the bridged -tee oscillator. In that type of 
circuit, an RC tee-network is bridged by 
either a resistor or a capacitor. If the series 
elements of the tee-network are capaci- 
tors, then the bridging element will be a 
resistor (Fig, 5% If the series elements are 
resistors, then the bridging element will 
be a capacitor (Fig. 6). 

Generating sinewaves 

As we have seen, the output amplitude 
of many sinewave oscillators tends to be 
unstable. On the other hand, the output 



ilt from a fixed- and a variable-frequency oscillator, 
and that signal is then filtered and amplified for 

Extracting a sinewave from a wave of 
some other shape is possible because all 
non-sinusoidal waveforms are composed 
of a number of sinewaves summed to- 
gether. The squarewave and the triangle 
wave, for example, contain a sinewave at 
the fundamental frequency and a n timber 
of harmonics (multiples) of the funda- 
mental frequency. For example, a square- 
wave with a fundamental frequency of 
200 Hz would be composed of a 200-Hz 
sinewave, plus400-Hz. 600-Hz. 800-Hz, 
, , . sinewaves. 

If we filter out all of the harmonics, 
we'll be left with a sinewave at the funda- 
mental frequency. The purity of the sine- 
wave can be quite good, especially if a 
high order of filtering is used. As shown in 
Fig, 7. we can use a lowpass or bandpass 
filter. 

Wide-range oscillators 

Another way to bypass the limited fre- 
quency range of an RC oscillator is to use 
a dual-oscillator circuit: that type of cir- 
cuit was popular in the 1950's. As shown 
in Fig. 8, the frequency of one oscillator is 
fixed (at 100 kHz); theotheroscillatesata 
variable frequency (80-100 kHz) that is 
determined by the user. Both oscillators 
are LC types. 

Their signals are fed to a non-linear 
mixer, the output of which is a new signal 
whose frequency is equal to the difference 
between the frequencies of the two input 
signals. That signal is sent through a 
lowpass filter to remove residual traces of 
,/j and/,, and then to an amplifier and the 
outside world. 

For example, when/, is 100 kHz, the 
difference between /, and/, is Hz, so 
there is no output. However, when/, is 80 
kHz, the output frequency is 
100 - 80 = 20 kHz. So the output frequen- 
cy may vary from to 20 kHz. 

In our next installment we'll discuss 
RC triangle wave and squarewave os- 
cillators; in addition we'll introduce the 
monostable multivibrator circuit'. R-E 



60 




D 




OJ 



LT 



IF YOU HAVE EVER DESIGNED AN ELEC- 

tronics projccl, you probably know that 
the job goes faster with an organized 
method for documenting the device as you 
build it. Despite that, diagrams and notes 
are usually produced as an afterthought, 
especially by less experienced designers. 
But rather than being a chore, or some- 
thing that slows down the process of get- 
ting a project up and running, effective 
documentation can greatly reduce the 
time it takes to design an effective eircuit, 
Thai's because poor documentation, or 
none at all, can cause design errors and 
construction mistakes, and constant rc- 
checking; that can make building of a 
project drag on for weeks when it really 
should lake only days. 

To focus on methods for applying pa- 



perwork to electronics construction proj- 
ects, this article splits the re cord- keeping 
task into manageable pieces. We' II look at 
a drawing plan that can be used to com- 
pletely describe any type of electronics 
equipment, and we'll show you how to 
make that plan a part of the creative pro- 
cess as you design your own project. We'll 
also show you a way to keep track of 
circuit wiring during the construction 
phase of your project. It can be applied to 
point-to-point, wire-wrap, or PC-board 
construction and automatically shows 
what has been connected to what, and 
simplifies keeping track of progress. 

Starting the paper trail 

The process of getting an idea, diddling 
with it, deciding to do it, then establishing 
a formal set of drawings to control the 
project is shown in block-diagram form in 
Fig. I. If you follow the procedure shown, 
when you finish you'll have a document 
that fully describes the device, the hard- 
ware housing it, and the history of your 
experience with it. The documentation 
process does not take long. Instead, it 




From Brainstorm 



- 









DAVID J. SWEENEY 







to Bread Board 

There are a lot of twists in the road between a good idea 

and a properly working circuit. In this article we'll 

show you how good paperwork, like a good map, 

can keep you from getting lostl 



m W> 



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1 



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CD 



61 



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DC 



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CHASSIS 

HARDWARE 

CIRCUIT BOARD TERM, 

PANEL MOUNTED PARTS 

DIMENSIONS 



CIRCUIT BOARD 

PARTS LAYOUT 

FOIL PATTERN 
(IF ETCHED BOARDI 



BLOCK DIAGRAM 
(IF WARRANTED! 



BUILD 

FOLLOW STEP BY STEP 
PROCEDURE 

STICK TO THE PAPER- 
WORK 



FIG. 1— THIS FLOW CHART shows the proper sequence of steps for turning your brainstorm into a 
properly working project. 



saves time. You begin in the "diddle" 
stage. 

During the diddle stage, the idea ger- 
minates. You sketch a schematic, make 
some changes, theorize about how the 
circuit works, and decide whether you 
have the time and money to build the de- 
vice. The device requires controls, so you 
diddle with the front- panel layout, add 
more controls, and imagine how nice the 
device will look. You might also consider 
the possibility of using parts from your 
junk-box. Perhaps you can use the audio 
section from a portable stereo you stopped 
using long ago or the control board from a 
mothballed printer. In addition, you 
might search a library for books or maga- 
zines with useful information. 

After diddling with the various aspects 
of the project, you enter the "go" stage. 
In the go stage, you gather the informa- 



tion that forms the basis for the project . 
First, open a document file. Enter the 
name of the project, the purpose of the 
device, any preliminary sketches, and a 
list of the parts you will need. Also, estab- 
lish a project kit — simply a box for keep- 
ing the construction materials as you 
acquire them. If the idea requires a lot of 
complex circuitry, generate a block di- 
agram and place it in the file. If a maga- 
zine article sparked the project, it, too. 
should go in the file. Finally, any other 
information regarding use or purpose 
should he included. 

You're entering all of that information 
for a good reason: If you get sidetracked 
for a while, when you get back to the 
project you could find that you have for- 
gotten some of the details. A lot of very 
good ideas get lost that way. 

After you've completed the steps out- 



lined in the go stage, it's time to make the 
drawings that will become the formal doc- 
umentation for the project. Four separate 
drawings should be made. Those arc cab- 
inet layout, chassis layout, schematic, and 
circuit layout. All of the drawings must 
coordinate with each other. If done prop- 
erly, those drawings will contain all the 
information required to completely de- 
scribe any device under construction. 

Cabinet 

In many ways, the cabinet design is the 
one from which all of the other designs 
evolve. That's because the cabinet's de- 
sign can directly affect any of the subse- 
quent drawings. Even a simple change 
can affect the layout of the chassis or the 
circuit board. Those changes can, in turn, 
cause changes in the appearance of the 
schematic. 

When designing the cabinet, thought 
should be given to both function and aes- 
thetics; after all, the cabinet is the "inter- 
face" between the user and the device. 
More is involved here than mere ap- 
pearance. Careful design should consider 
the mechanical factors in the operation 
and mounting of the various potentiome- 
ters, trimmers, switches, jacks, meters, 
displays, or what have you. Some consid- 
erations are obvious — spacing between 
controls must be sufficient to allow for 
comfortable operation. Others, however, 
may not become apparent until after 
you've cut the mounting holes. What may 
be a relatively small knob on the exterior 
can be attached to a relatively large rotary 
switch on the interior. If spacing is too 
tight, there might be insufficient clear- 
ance to mount all of the controls. To avoid 
such problems, consider all of the phys- 
ical requirements for the cabinet as you 
design the unit's appearance. 

Chassis 

That drawing indicates the relative lo- 
cation of circuit boards, includes hard- 
ware dimensions and mounting holes, and 
locates any other parts that are mounted 
inside the cabinet. The identification of 
the electrical components should match 
the identification in the schematic. For 
example, if the panel-mounted potenti- 
ometer that controls the frequency of a 
function generator is called R4 in the 
schematic, it should be labeled R4 in the 
chassis diagram. In the cabinet drawing 
that control might have been labeled fre- 
quency: such labeling is acceptable for 
that drawing only. 

In the chassis drawing, the circuit 
board or boards, regardless of their actual 
component count, are treated as units. 
Components that are located off the cir- 
cuit boards should be shown in their rela- 
tive positions so that they are easy to spot, 
but interconnecting wiring should not be 
shown. Showing such wiring would add 
continued on peine 94 



62 



vCzL! d lLfizLUJ L 




THE VERSATILE 4007 

Need a versatile CMOS building block for a one-of-a-kind application? Then the 4007 is for 
you. Find out how to use it here. 



RAY MARSTON 



THli J()C>7 IS THE SIMPLEST KIN THE CMOS 

line. It contains just iwo pairs of comple- 
mentary MOSFETs and a CMOS inver- 
ter. However, each element is indepen- 
dently accessible, so the elements can be 
combined in a great variety of ways. In 
fact, the 4007 is sometimes known as the 
"design-it-yourself" CMOS IC, as it can 
function as a digital inverter, a nand or a 
nor gate, or an analog switch. It can also 
In net ion as a linear device. 

Therefore, not only is the 4007 the sim- 
plest CMOS IC, but it is also the most 
versatile. And that makes it an ideal de- 
vice for demonstrating the principles by 
which CMOS devices operate to students, 
technicians, and engineers. In this article 
we'll examine the 4007 from both the- 
oretical and practical points of view, and 
we'll include many circuits that you can 
use as-is in your next design. 

Basic digital operation 

The mils of the 4007 are shown in Fig. 
1. All MOSFET's in the 4007 are enhan- 
cement-mode devices; Ql, Q3, and Q5 
are p-channel, and Q2, Q4. and Q6 are n- 
channel types. The drains and sources of 
MOSFET's QI-Q4 are independent; the 
drain of Q6 is connected to the drain of 
Q5, so those two MOSFET's compose the 
inverter mentioned above. Each pair of 
transistors is protected by a network like 
the one shown in Fig. 2. 





FIG. 1— THE 4007 IS COMPOSED OF three pairs of complementary enhancement- mode MOSFET's. 



FIG. 2— INPUT PROTECTION CtRCUiTRY 
H1,D1-D3) of each pair of MOSFET's is shown 
here. 



As you recall, the term CMOS is an 
acronym forComplementary Metal Oxide 
Semiconductor; it is fair to say that most 
CMOS IC's arc designed around CMOS 
devices like those that compose the 4007. 
Therefore it is worthwhile to get a good 
understanding of how those elements 
work. Let's look first at their digital 
characteristics; later well examine them 
in light of their analog capabilities. 

The two fundamental characteristics of 
a MOSFET are as follows. First, the gate, 
or input terminal, of a MOSFET has a 
near-infinite impedance. Second, the 
magnitude of the voltage applied to the 
gate controls the magnitude of drain-to- 
source current Row. 

In an enhancement-mode h- channel 
MOSFET the drain-to-source circuit is a 
high impedance when the gale is at the 
same potential as the source. However, 
that impedance decreases as the potential 
applied to the gate becomes positive with 
respect to the source. So an n-channcl 
MOSFET can be used as a digital inverter 
by wiring it as shown in Fig. 3-a. With a 
low applied to its input the MOSFET is 
cut off, so the output goes high. With a 
high applied to its input the MOSFET 
saturates, so the output goes low. 

In a /.(-channel enhancement-mode 
MOSFET the drain-to-source circuit is 
also a high impedance when the gate is at 
the same potential as the source. But. 
unlike the n-channcl device, that imped- 



ance decreases as the potential applied to 
the gate becomes negative with respect to 
the source. So a p-channel MOSFET can 
be used as a digital inverter by wiring it as 
shown in Ftsr. 3-6. 




FIG. 3— A DIGITAL INVERTER can be built from 
either an n-(a) or a p-channel MOSFET (ft). 

In both n- and p-channel inverters, the 
amount of current that Hows through the 
device is limited by the value of Rl. And 
both circuits draw a finite quiescent cur- 
rent in the on state. However, quiescent 
current drain can be reduced in almost 
zero by connecting a pair of complemen- 
tary MOSFET's as shown in Fig. 4. 



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CO 

m 
co? 

00 

01 

63 




FIG. 4— THE STANDARD CMOS INVERTER is 
built from two stacked MOSFET'S. 



40 





















V TH 
1 
1 / 


I I I I 


I 1 1 I 



30 



fSo 



10 



5 ID 15 

V GS -VDLTS 

FIG. 5— THE N-CHANNEL MOSFET conducts al- 
most no current until V GS exceeds about 2. volts. 



W 
O 

Z 

o 
cc 
I- 
u 



LU 

o 

Q 

< 

cc 




6 INPUT 



FIG. 6— LINEAR OPERATION OF A 4007 
MOSFET requires simple biasing (a); very high 
input impedance is achieved by the addition of 
R4 (b). 



In lhat configuration, which is standard 
for many CMOS inverters and buffers, 



wiih a low applied to the input, Ql is on, 
so the output is high. However. Q2 is off, 
so no qutesceril current can Bow. With a 
high applied to the inpui. 02 is on, so the 
output is low. In that ease Ql Ls off. so 
quiescent current How is still nil. Of 
course, there is no requirement that the 
MOSFETs be operated solely in the digi- 
tal mode; let's find out how they can be 
used otherwise. 

Basic linear operation 

To understand the operation of CMOS 
circuitry, it is essential to understand the 
linear characteristics of the basic 
MOSFET. Figure 5 shows the typical 
gate- voltage (V GS ) to drain-current (1 D > 
curve or an n-channel enhancement- mode 
MOSFET Note that negligible drain cur- 
rent Hows until the gate votage rises to a 
threshold value. V TH , of about 1.5 to 2.5 
volts. After that point, however, drain cur- 
rent increases almost linearly with further 
increases in gate voltage. 

Figure 6-a shows how to connect an n- 
channel MOSFET as a linear inverting 
amplifier. Resistor Rl is the drain load, 
and R2 and R3 bias the gate so that the 
device operates in the linear range. The 
value of R3 must be selected to give the 
desired quiescent drain current; it nor- 
mally ranges from 18-I00K. To provide 
the linear amplifier with a very high input 
impedance, wire a 10- megohm resistor 
(R4) as shown in Fig. b-b. 

Figure 7 shows typical VI charac- 
teristics of an n-channel MOSFET at vari- 
ous fixed values of V GS . To understand 
that graph, imagine that, for each curve, 
V GS is fixed at V DD . but that V DS can be 
varied by altering the value of the drain- 
load resistor. The graph can then be divid- 
ed into two characteristic regions, as indi- 
cated by the dotted line: the ohmic region 
and the pinch-off region. 

For each curve shown in Fig. 7, the 
beginning of the pinch-off region — the 
point where the dashed line crosses the 
solid line — is called the pinch-off volt- 
age, or Vp, which is the value of V ns 
above which l [3 increases little, if at all. 
for further increases in V| )S . 

When the MOSFET is in the pinch-off 
region and V DS is more than 50% of V GS , 
the drain functions as a constant-current 
source. The amount of current lhat flows 
is controlled by V c;s . A low value of V c;s 
gives a low current flow, and a high value 
of V t;s gives a high current How. Those 
saturated constant-current characteristics 
protect CMOS devices from short-circuit 
failure and also determine operating 
speed at various supply voltages. Both 
current-drive and operating speed in- 
crease in proportion to the supply voltage. 

When the MOSFET is in the ohmic 
region and V |)s is less than 50% of V (;s , 
the drain functions as a voltage-controlled 
resistance. That resistance increases ap- 
proximately as the square of V GS . 







/ 






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REGION / 


1 


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1 SATURATED 
1 REGION 


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1 / I 


V GS luv 




if * 

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K V GS " SV 




] 


5 10 15 



FIG. 7— AN N-CHANNEL MOSFET operates lin- 
early in the ohmic region above the dashed line 
and digitally in the pinch-off region below the 
dashed line. 



II 



V 0B =1DV 


\V D n=15V 




V DB = 5V 








I 







5 10 15 

v IN - VOLTS 

FIG. 8— VOLTAGE-TRANSFER characteristic of 
the CMOS inverter (Fig, 4) reveals that, for in- 
puts near ground and V DD , output changes very 
little. 




C2 
.47 
if-— o OUTPUT 



FtG. 9— LINEAR OPERATION of the inverter {Fig. 
4) is possible, as shown here. 

Figure 8 shows typical voltage-transfer 
characteristics of the standard CMOS in- 
verter at different supply voltages. Note 
that when V |)n is 15 volts, the output volt- 
age changes a very small amount when 
the input voltage is near either zero or 
V J)n . However, when the input voltage is 
biased at roughly V m) /2, a small change 
in input voltage produces a large change 
in output voltage. Typically, the inverter 
has a voltage gain of about 30 db when 
used with a 15-volt supply, and 40 db at 5 
volts. Figure 9 shows how to connect the 
CMOS inverter for use as a linear ampli- 
fier; the circuit has a bandwidth of 710 
kHz at 5 volts, and 2.5 Mhz at 15 volts. 

We can wire three simple CMOS inver- 
ters (like the one shown in Fig. 4) in series 



64 



V orj = 15V 

Vdo'IDV 


— s 






v DD =sv 








"s 


s. 


i 


>* 





5 10 15 

V| N -VOLTS 

FIG. 10— VOLTAGE-TRANSFER characteristic of 
a B-series CMOS inverter is similar to that of the 
simple inverter. 



15 



< 

6 













, V DD " 15V 


j&Svv 


S DD =1tlV 

" 5V x_ 





FIG.11— DRAIN CURRENT of the simple Inverter 
peaks at an input voltage just over V DD .2. 




3 h 

FIG. 12— DISABLE AN UNUSED INVERTER pair 
as shown here; Q1 and Q2 are disabled as in a; 
03 and Q4 as in b; Q5 and 06 as in c. 



INPUT 



1 




INPUT 

) 

OUTPUT 



OUTPUT 

6 
INPUT 



OUTPUT 



FIG. 13— EACH PAIR OF TRANSISTORS may be 
used independently as an inverter. 

to obtain the direct equivalent of a modern 
"buffered" B-series inverter, which has 
the overall voltage transfer curve shown in 
Fig. 10. A B-series inverter typically gives 



about 70 db of linear voltage gain, but it 
tends to be quite unstable when used in the 
linear mode. 

To finish up our discussion of basic 
operation , take a look at Fig, 1 1 . Shown 
there is the drain-current transfer charac- 
teristics of the simple (non-buffered) 
CMOS inverter. Note that drain current is 
zero when input voltage is zero or V DD . 
However, in the middle range, current 
rises to a maximum value when the input 
is at approximately V DD /2, at which point 
both MOSFET's are on. That on current 
can be reduced by wiring resistors in se- 
ries with the source of each MOSFET. 
We'll use that technique in the "micro- 
power" circuits discussed below. 

Basic rules 

There tire a few basic rules to follow in 
order to use the 4007 successfully. First, 
you must ensure that all unused elements 
of the devices are disabled. A pair of 
MOSFET's can be disabled by con- 
necting them as an inverter and grounding 
their inputs. As shown in Fig. 12-a. to 
disable the Q1-Q2 pair, just ground pin 6. 
To disable the other pairs, in addition to 
grounding the inputs, the sources and 
drains must be connected to ground and 
+ V as shown in Fig. 12-/? and Fig. 12-c. 

In use, the input terminals must not be 
allowed to rise above V Dr) (the supply 
voltage) or below ground. To use an it- 
ch annel MOSFET, the source must be 
tied to ground, either directly or through a 
current-limiting resistor. To use a p-ehan- 
nel MOSFET, the source must be tied to 
V|, n , either directly or through a current- 
limiting resistor. 

Digital circuits 

A single 4007 can be configured as 
three independent inverters, as shown in 
Fig. 13. In that figure, and in others that 
follow, we won't necessarily show all de- 
tails of how to wire the circuit under dis- 
cussion. Also, multiple pin connections 
that terminate in a single function will he 
shown as in Fig. 13. For example, the 
output of the QI-Q2 inverter in that figure 
is obtained by connecting pins 13 and 8 
together. 

Figure 14 shows how to connect the 
4007 as one inverting and one non-invert- 
ing buffer. In the non-inverting circuit. 
the QI-Q2 and Q3-Q4 inverters are sim- 
ply wired in series to provide two stages of 
inversion — which provides a non-invert- 
ing buffer. 

The maximum source (load-driving) 
and sink (load-absorbing) currents of a 
simple CMOS inverter are about 10- — 20 
mA when either output MOSFET is fully 
on. To increase that sink current, several 
n-channel MOSFET's can be connected 
in parallel in the output stage. Figure 15 
shows how to configure the 4007 as a high 
sink-current inverter. Similarly, Fig. 16 
shows how to configure the 1C as a high 




OUTPUT 6 

INPUT 
INVERTER 



INPUT 



T 




OUTPUT 



FIG. 14— A NON-INVERTING BUFFER is com- 
posed of two inverters connected in series 
(Q1-Q4). The other inverter (0.5 and 06) can be 
used independently. 



— IHHI4H 



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OUTPUT 




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r< e )J H I r\s >-l Eri 



-t 



6 INPUT 






FIG. 15— SINK CURRENT may be increased by 
connecting the n-channel MOSFET's in parallel. 



■ -rid (12)- 




6 INPUT 



FIG. 16— SOURCE CURRENT MAY BE IN- 
CREASED by connecting the p-channel 
MOSFET's in parallel. 

source-current inverter. Last. Fig. 17 
shows how to connect all the elements of a 
4007 in parallel to produce a single inver- 
ter that will both sink and source three 
times the current of a standard inverter. 

Logic circuits 

The 4007 is well-suited for demonstrat- 
ing the basic principles of CMOS logic 



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FIG. 17— BOTH SINK AND SOURCE CURRENT 
may be increased by connecting all transistors 
of each type in parallel. 




INPUTS 

FIG, 18— A TWO-INPUT NOR GATE can be built 

from a 4007. 

gales. Hgure 18 shows how to configure 
the 4007 as a 2-input nor gate. In thai 
circuit two n -channel MOSFET's are 
wired in parallel so that either can pull Ihe 
output to ground with a high input. Also, 
two p-channcl MOSFET's arc wired in 
series so that, wilh low inputs, both must 
turn on to pull the output high. Figure 19 
shows how to wire up a 3-input nor gale; 



il is composed ol' three series- and ihree 
para I lei -connected MOSFET's. and its 
principle ofoperalkm is ihc same as ihe 2- 
inpul circuit. Figure 20 shows how to con- 




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1101(61 f3) 



INPUTS 






FIG. 19— A THREE-INPUT NOR GATE can be 
built from a 4007. 



+V 




{" 




| 1 1-* 1 1 



Li 

,Q1 X 



'-(13) 



1 ij I 

u 



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l 1 s H 






1 

i— — 1 1 )~-i 



I 

1 03 



1 



-X-o 



OUTPUT 



I 



(3 H 6) 



INPUTS 

FIG. 20— A TWO-INPUT N AND GATE can be built 
from a 4007. 



figure the 4007 as a 2-input nand gate. 
When both inpuis are high. Q2 and Q4 
both lurn on, so the output goes low. Oth- 
erwise Ql or Q3 pull the output high. 

An important element of many digital 
circuits is called an analog swiich. il is an 
electronically-controlled SPST, SPDT. or 
other switch. The principle of the SPST 
type is shown in Hg. 2\-a. When the con- 
trol input is high, signals can flow be- 
tween points x and y unimpeded. When 
that input is low, no signal can flow. 

The 4007 analog swiich has a near- 
infinite off resistance and an on resistance 
of about 600 ohms. It can handle signals 
between zero volts and the positive supply 
voltage. And since the gate is bilateral, 
terminals x and y can function as either 
input or output. 



^° 



CONTROL INPUT 




r^ir^r 



L Q3_^ 



_ J 



x — 

(14)--, 



J 



1 ' 



!01 




i 

— iih 
! ,J 

4-1 a : 

i i 

1~ 



*+v 



FIG. 21— AN SPST ANALOG SWITCH can be 
built from a 4007. 

Circuitry to implement the SPST 
swiich is shown in Fig. 2\-b. An n-ehan- 
nel and a p-channel MOSFFT are wired in 
parallel (source-to-sourcc and drain-to- 
drain), but their gate signals arc applied 
oul of phase by means of Ihe Q1-Q2 inver- 
ter. To turn the Q3-Q6 pair of transistors 
on, Q6's gate must be high, and Q3"s gate 



66 



low; to turn ihe switch oil, the opposite 
conditions must be present. 

An SPDT analog switch is shown in 
Fig. 22-«; circuitry which accomplishes 
that function is shown in Fig. 22-b. Here 
two transmission elements are connected 
in parallel, but their control voltages are 
applied out of phase, so that one switch 
opens when the other closes, and vice 
versa. 

We saw earlier that the 4007 can also be 
used in a linear mode; now let's look at 
how to do that, and at the sort of perfor- 
mance we can expect from a linearly- oper- 
ated 4007. 



A 




X 




~~ ' ^T-O 






1 




B 






o 







CONTROL INPUT 




FIG. 22— AN SPDT ANALOG SWITCH can be 
built from a 4007. 



Linear circuits 

Figure 23 shows how voltage gain and 
frequency response vary according to sup- 
ply voltage. The curves shown in that fig- 
ure assume that the 4007 is driving a high- 
impedance (10 megohm), low-capaci- 



>2D 





Vc 


c4 












v c 


c^v 




\ 


^ 






Vc 


; = 15V 




■^ 














\! 
















N 


\\ 



10 


t id to 2 itr io* to 5 in 6 io' io 8 

FREQUENCY-Hz 

FIG. 23— FREQUENCY RESPONSE and voltage 
gain of a linear-mode CMOS amplifier is depen- 
dent partially on supply voltage. 

tance (15 pF) scope probe. The output 
impedance of the open- loop amplifier typ- 
ically varies from 3K (at 15 volts) to 5K (at 
10 volts) to 22K (at 5 volts). The product 
of the output impedance and the ouput 
load capacitance determines the circuit's 
bandwidth. Increasing either load capaci- 
tance or output impedance decreases 
bandwidth. 

As you can see in the voltage transfer 
curve back in Fig. 8, the distortion charac- 
teristics of the CMOS linear amplifier are 



< 



lb 








10 








s 

n 









5 10 15 

V D0 - VOLTS 

FIG. 24— VERY LITTLE CURRENT FLOWS until 
Vnr, exceeds 5 volts. 



1— *+V 



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input r~ f " , -'">-i 
I 






|Q5 



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R3 
10M 

r 










TABLE 1— 




LINEAR-MODE PERFORMANCE 


R1/R2 


Io 


Av 


Band- 
width 





12.5mA 


20 


2.7 MHz 


loon 


8.2mA 


20 


1.5 MHz 


5601! 


3.9mA 


25 


300 kHz 


1K 


2,5mA 


30 


150 kHz 


5.6K 


600u.A 


40 


25 kHz 


10K 


370uA 


40 


15 kHz 


100K 


40|j.A 


30 


2 kHz 


1MEG 


4pA 


10 


1 kHz 



FIG. 25— SOURCE RESISTORS R1 AND R2 de- 
crease current consumption drastically. 



not particularly impressive. Linearity is 
good for small-amplitude signals, but dis- 
tortion increases progressively as the out- 
put swing approaches the upper and lower 
limits of the power supply. 

Figure 24 shows the typical drain-cur- 
rent versus supply- voltage charcteristie of 
the basic CMOS linear amplifier. Note 
that supply current typically varies from 
0.5 mA at 5 volts to 12,5 mA at 15 volts. 

As we mentioned above, in many ap- 
plications, the quiescent supply current of 
a 4007 CMOS amplifier often can be re- 
duced (at the expense of reduced band- 
width) by wiring external resistors in 
series with the source terminals of the two 
MOSFET's. In Fig. 25 we show how a 
micropower circuit would be configured. 

It is important to understand that the 
source resistors increase the output im- 
pedance of the amplifier, output imped- 
ance is roughly equal to the product of Rl 
and A v . That impedance, and the resis- 
tance and the capacitance of the load af- 
fect the circuit's gain and bandwidth. 

Table I shows how supply current, volt- 
age gain, and bandwidth vary with the 
value of those source resistors. As you can 
see, with 10K source resistors, bandwidth 
is about 15 kHz. However, by increasing 
load capacitance to 50 pF, bandwidth de- 
creases to about 4 kHz; by reducing ca- 
pacitance to 5 pF, bandwidth increases to 
45 kHz. Similarly, reducing the resistive 
load from 10 megohms to 10 kilohms 
causes voltage gain to fall to unity. The 
conclusion is that, to obtain significant 
gain, load resistance must be large rela- 
tive to the amplifier's output impedance. 

An unbiased 4007 inverter has an input 
capacitance of about 5 pF and an inpul 
resistance near infinity. So, if the output of 
the circuit in Fig. 25 is fed directly to the 
input of another 4007 stage, the overall 
voltage gain will be about 30 dB. and the 
bandwidth will be about 3 kHz, Those 
values will be obtained when Rl has a 
value of I megohm. For extremely low 
current drain (.4 pA!). Rl could be in- 
creased to 10 megohms. 

Now vou can see why we said that the 
4007 is the most versatile CMOS 1C. With 
the ideas we've presented here, you 
should have no trouble thinking of many 
more applications for the 4007. R-E 



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67 






Where's Your ELECTRONICS Career Headed? 



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The Move You Make Today Can Shape Your Future 



Yes it's your move. Whether on a chess board 
or in your career, you should plan each move 
carefully. In electronics, you can move ahead 
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PC Service 



One of the most difficult tasks in build- 
ing any construction project featured in 
Radio-Electronics is making the PC 
board using just the foil pattern provided 
with the article. Well, we're doing some- 
thing about it 

We've moved all the foil patterns to this 
new section where they're printed by 
themselves, full sized, with nothing on the 
back side of the page. What that means 
for you is that the printed page can be 
used directly to produce PC boards! 

Note: The patterns provided can be 
used directly only for direct positive pho- 
toresist methods. 

In order to produce a board directly from 
the magazine page, remove the page and 
carefully inspect it under a strong light 
and/or on a light table. Look for breaks in 
the traces, bridges between traces, and in 
general, all the kinds of things you look for 
in the final etched board. You can ciean up 
the published artwork the same way you 
clean up you own artwork. Drafting tape 
and graphic aids can fix incomplete traces 
and doughnuts, and you can use a hobby 
knife to gel rid of bridges and dirt. 

An optional step, once you're satisfied 
that the artwork is clean, is to take a little 
bit of mineral oil and carefully wipe it 
across the back of the artwork. That helps 
make the paper transluscent. Don't get 
any on the front side of the paper (the side 
with the pattern) because you'll con- 
taminate the sensitized surface of the 
copper blank. After the oil has "dried" a 
bit — patting with a paper towel will help 
speed up the process — place the pattern 
front side down on the sensitized copper 
blank, and make the exposure. You'll 
probably have to use a longer exposure 
time than you are probably used to. 

We can't tell you exactly how long an 
exposure time you will need but, as a start- 
ing point, figure that there's a 50 percent 
increase in exposure time over litho- 
graphic film. But you'll have to experiment 
to find the best method for you. And once 
you find it, stick with it. Don't forget the 
"three C's" of making PC boards — care, 
cleanliness, and consistency. 

Finally, we would like to hear how you 
make out using our method. Write and tell 
us of your successes, and failures, and 
what techniques work best for you. Ad- 
dress your letters to: 

Radio- Electronics 

Department PCB 

500-B Bi-County Blvd. 

Farmingdale, NY 11735 




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OUR ELECTRONIC SCARECROW can help chase away a less than determined burglar. If you chose to 
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BECAUSE OF THE DANGEROUS VOLTAGES that the Stun gun develops, be extra careful when laying 
out and etching this PC pattern tor that circuit. go 

m 

3 

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CD 

m 



69 



PC Service 



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— I 
LU 

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70 



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71 



Satellite TV 



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Microwave test equipment 



WHEN THE FIRST HOME SATELLITE DISH 

systems appeared in the market- 
place late in 1979, they were priced 
at just under $4,000 (wholesale). 
Most people were astounded that 
so complex a system could be as- 
sembled for so small an amount of 
money. Competition and tech- 
nological evolution have improved 
things to the point that today a 
system with similar (or improved) 
performance characteristics sells 
for as little as $350 (wholesale). 
However, it is not just the dish sys- 
tems themselves that have bene- 
fited from the on-going evolution 
in electronics. 

In fact, the growth of TVRO has 
fueled a number of innovations in 
the microwave area, but none is 
more dramatic than the innova- 
tions in microwave test equip- 
ment. And that new equipment 
surely must must frighten old-line 
builders of microwave test instru- 
ments such as Hewlett Packard. 
The spectrum analyzer is a case in 
point. High-performance spec- 
trum analyzers have always cost an 
arm and a leg. The most important 
factors to consider include: max- 
imum operating frequency, reso- 
lution, sensitivity, and stability. 

The unit shown in Fig, 1 is a good 
example of a low-cost, high-per- 
formance spectrum analyzer. 
We'll discuss it in detail below, but 
for now let's consider some of the 
problems involved in setting up a 
TVRO system, and how a spectrum 
analyzer can help. 

Installation 

Installing a small-dish satellite- 
receiving system (whether for vid- 
eo, audio, or data communication) 
has changed little since 1979. First 



the components of the system 
must be brought together. Then 
the dish must be erected on its 
mount and outfitted with the nec- 
essary electronics. Last, the dish 
must be aimed at the desired satel- 
lite, which is located some 24,000 
miles away. 




FIG. t 

The aiming process is compli- 
cated by the number of satellites 
now in operation, by those soon to 
be, and by the rapidly expanding 
use of the same frequency band 
(3,700 to 4,200 MHz) for point-to- 
point terrestrial communications. 
In short, there are many possibly 
interfering signal sources, and 
only one is right for a particular 
installation. 

Of all of the instruments de- 
signed to measure the strength 
and quality of a microwave signal, 
none approaches the spectrum 
analyzer for either accuracy or 
spectral integrity. Unfortunately, 
however, until very recently the 
cost of a good microwave spec- 
trum analyzer made those less- 
accurate instruments more attrac- 
tive than they, on their own merits, 
deserved. 

A breakthrough 

The good news is that the same 
technology that made it possible 




BOB COOPER, JR., 

SATELLITE-TV EDITOR 



TVRO dealer "Starter Kit" 
available 

Bob Cooper's CSD Magazine has ar- 
ranged with a number of TVRO equip- 
ment suppliers to provide a single- 
package of material that will help intro- 
duce you to the world o( TVRO dealership. 
A short booklet written by Bob Cooper 
describes the start-up pitfalls to be avoid- 
ed by any would-be TVRO dealer, in addi- 
tion, product data and pricing sheets from 
prominent suppliers in the field are in- 
cluded. That package of material is free of 
charge and is supplied to firms or individu- 
als in the electronics service business as 
an introduction to the 1984,"85 world of 
selling TVRO systems retail. 

You may obtain your TVRO Dealer 
Starter Kit free of charge by writing on 
company letterhead, or by enclosing a 
business card with your request. Address 
your inquiries to: TVRO STARTER KIT, 
P.O. Box 100858, Fort Lauderdale, FL 
33310. That kit not available to individuals 
not Involved In some form of electronics 
sales and service. 



for the price of a TVRO receiver to 
drop by a factor of 10 (or even 20) 
has now been applied to the spec- 
trum analyzer. In fact, an entirely 
new generation of microwave test 
instruments is now available; 
many are priced at 10% or less of 
the cost of the older HP-style units. 
And they have been designed from 
the ground up to be portable, self- 
powered, field-usable instru- 
ments. 

One portable spectrum ana- 
lyzer is made by AVCOM of Vir- 
ginia Inc., (500 South Lake Blvd., 
Richmond, VA 23235), a veteran of 
the satellite-TV field. The PSA-35, 
shown in Fig. 1, offers six bands of 
coverage as follows: 

• Below 10 MHz to 770 MHz 

• 270 MHz to 770 MHz 



72 



A NEW KIND OF MAGAZINE FOR ELECTRONICS PROFESSIONALS 



<&., 



\'X-' 



SOUP UP YOUR PC 

How to turbocharge your computer 



' v ■■-'•■ : ■'-.' 



■■'■■■■.'•. 



•A\<\,V. 






HfaKftS 



^M 



m 



m 



PUBLICATION 




OPTICAL DISKS 

Tomorrow's memory technology 

OKIDATA UPGRADE 

Enhancing the Okidata Printer 






Mfl6 



fUMrSL 



CONTENTS 



Vol. 3 No. 9 



September 1986 



7 CB Scanner 

Take that CB off the shelf, good buddy! Here's how to use your 
computer to scan the channels you select, and without having to flip 
the switch! Frank P. Maloney 

11 Soup Up Your PC 

Here's how to change chips and set yourself some turbocharged 
performance with as much as a 30% improvement. TJ Byers 

14 Optical Disks 

In the near future, those compact discs now used in classy stereo 
equipment may be finding their way into your computer system 
where they'll be doing yeoman service as storase devices. 
Marc Stern 

3 Editorial 

4 Letters 

4 Computer Products 

5 Software Review 




See Page 7 




See Page 14 



ON THE COVER 

you can make your PC perform like the beautiful IBM PC/AT shown 
on this month's cover. For full details, see the article that starts on 
page 11 or buy one of the new ones from IBM! 



COMING NEXT MONTH 

Man, have we got a fantastic line-up for you! We're kicking off this 
issue with a Graphic Biofeedback monitor that does everything but 
feed you tranquilizers. Then there's a TVRO antenna pointer that 
gives you all the numbers via computer Finally you'll find a story 
on how to upgrade your Okidata printer. Don't miss it. 




2 ComputerDigest — SEPTEMBER 1986 



EDITORIAL 



Told ya so\ 



■The shaking-out period is just about over. For awhile back there, 
"computer" was a magic word that opened the bank. If you had a 
computer-oriented product, you automatically made lots of money 
Opportunists the world overjumped on the bandwason just as they did 
when "stereo" was the magic word, or "CB." 

And of course, magazines sprung up like weeds. Some long-established 
publications in the electronics industry changed their direction to cater to 
the new interest. At least one went so far as to change its name. So-called 
"vertical" publications appeared to cater to the purchasers of a particular 
brand of computer Newsletters appeared all over the place to cater to 
particular interests. And people who had never before been in the 
publishing business now saw reason to give it a try 

Gernsback Publications, a long-established force in the communications 
industry took a different tack. ComputerDigest Magazine was brought out 
as a 16-page insert in the well-established Radio-Electronics Magazine. 
Readers who had long-subscribed to this publication, began to worry and 
wonder. Mail poured in from concerned readers who did not want the tail 
to wag the dog. Was their favorite magazine going to follow the others and 
become another Computer Magazine? Were more and more pages to be 
given over to computers until a full transistion had been made? 

We assured the readers that this would never be the case, and told them 
not to be concerned. 

ComputerDigest is now in its third year It still occupies only 16 pages, 
at no cost to the space allocated for Radio-Electronics. 

As we said at the start of this editorial, the shaking-out period is about 
ever. The many new businesses and new magazines that offered little more 
than another place to spend your money have dropped by the wayside. 
Those who are still in business will, no doubt, remain in business. 

We're glad we're still here. 

We told you! 



4 




Byron G. Wels 

Editor 



ComputerDigest is published monthly as an insert in Radio-Electronics magazine by Gernsback Publications, Inc.. 
500-B Si-County Blvd., Farrnincdale, N.Y. 11735. Second-Class Poslage Paid at New York, N.Y. and additional 
mailing offices. Copyright r- 19fl6 Gernsback Pubtications. Inc. All rtgnts resert/ed. Printed in U.S.A. 

A stamped self-addressed envelope must accompany all submitted manuscripts and or arlwork or photographs i( 
their relurn is desired should Ihey be rejected. We disclaim any responsibility for the loss or damage ol manuscripts 
and/or artwork or photographs while in our possession or otherwise. 



Computer 
Dices? 



M. Harvey Gernsback, 
editor-in-chief, emeritus 



Larry Steckler, 

EHF, CET: publisher & editor in chief 



Art Kleiman, 

editorial director 
Byron G. Wels, 

editor 
Brian C. Fenton, 
managing editor 

Carl Laron, 

associate editor 

Robert A. Young, 

assistant editor 

Ruby M. Yee, 

production director 

Karen Tucker, 

production advertising 

Robert A. W. Lowndes, 

production associate 

Geoffrey S. Weil, 

production assistant 

Andre Duzant, 

technical illustrator 

Jacqueline P. Cheeseboro 

circulation director 

Arlirte R. Fishman, 

advertising director 



Computer Digest 

Gernsback Publications, Inc. 

Executive offices 

500-B Bi-County Blvd., 

Farmingdale, NY 11735 

516-293-3000 

President: Larry Steckler 

Vice Presidenti Cathy Steckler 

ADVERTISING SALES 516-293-3000 

Larry Steckler 
Publisher 

NATIONAL SALES 

Joe Shere 

1507 Bonnie Doone Terrace 

Corona Del Mar, CA 92625 

714-760-8967 



SEPTEMBER 1986 — ComputerDigest 3 



LETTERS 



Hookup 

How can I adapt my Sinclair so I 
can plug it directly into a 
composite video monitor instead 
of using a TV set? How do you 
bypass the RF modulator? — J.D., 
Methuen, MA. 

At the very moment of this 



writing, we've got an author work 
on an article covering that subject 
Keep an eye on ComputerDigest. 



Users' Group 

A new international word 
processing users' group has been 
formed. It offers a bi-monthly 
newsletter, called SCROLL and 
we're planning our own national 
bulletin board system. A complete 




Simpson Model 383 
Digital Temperature Tester 
Does It All! 




• Dual Inputs — measure two temperature sources, switch-selectable 

• Differential and Normal Temperature Modes — automatically read the difference 
between two temperatures or each separately. Provides for accurate relative 
temperature determinations. Ideal for heating and air conditioning service and 
environmental monitoring 

• DC Millivolt Range — quick check of thermocouples, flame rods and other sensors 
■ Chart Recorder Output — provides 1 mV DC per degree F or C output with low 

source resistance for recording/controlling applications 

• Four Ranges: -30°Fto + 200°Fand +200°Fto +1200°F 

-34°C to +93°Cand +93°Cto +650°C 

• High Accuracy — 0.2% of reading + 1 °C (I.ST), from 0T to + 1000T 

• Switch-Selectable Centigrade or Fahrenheit Readout 

• Large, High-Contrast, 0.5" Liquid Crystal Display 

• Single 9 Volt Alkaline Battery 

• Humidity Kit, Disposable Thermocouples and Other Accessories Available 

Model 383, complete with test lead set, 4' J-type temperature sensor probe, 

9 V alkaline battery and operator's manual. Cat. No. 12415 $195.00 

AVAILABLE FROM LEADING ELECTRONICS/ELECTRICAL DISTRIBUTORS 



SIMPSON ELECTRIC COMPANY 

853 Dundee Avenue, Elgin, Illinois 60120-3090 
(312) 697-2260 • Telex 72-2416 • Cable SIMELCO 




ItMiTiuwnH^^^i^^l^TtccuBuT 



telecommunications package will 
be offered to all members. And a 
library of public domain and 
tutorial disks in over 100 different 
computer formats will be available 
to members. Cost is just $15.00 per 
year annual membership. Write to 
W/PUG, Box 144, Malverne, NY 
11565 or call me at (516) 746-0056. 

Could you give us a "plug" in 
ComputerDigest Magazine? — 
A.G., Malverne, NY 

No At, sorry We don't do that 

Help! 

I don't know a thing about 
computers, but my new secretary 
told me our old typewriter is 
passe. I was ready to buy a new 
one, but she suggested either a 
computer or at least an electronic 
typewriter I don't want to invest 
heavily and then find that massive 
training programs are required. 
What's your recommendation? — 
L.M., Great Neck, NY 

Go for the computer! (What else 
would I say?) Make sure you get a 
letter-quality printer with it and a 
good word processing program. 
Give her the instruction manual 
over a weekend, and when she 
comes in on Monday morning, 
stand back! The efficiency and 
throughput will floor you. 

Danger? 

My father tells me that there's a 
hazard of radiation exposure if I 
spend time in front of the VDT 
(Video Display Terminal). I say he's 
getting as much exposure from the 
TV set he's watching. — HS., Detroit, 
Ml. 

Try an experiment: Get some X- 
Ray film from your dentist, wrap 
one piece in lead foil as a control. 
Tape another piece to the CRT 
screen of your terminal, another to 
the TV screen. Rig another piece a 
foot away from each screen, still 
another two feet away Keep 'em 
in place for a week, then have 
them all developed, making sure 
they're numbered so you know 
which was where. With a 
densitometer or photographic light 
meter, you'll get relative indications 
of the exposure and the rate of 
decay of each through free space. 
Let us know how you make out! 



CIRCLE 206 ON FREE INFORMATION CARD 

4 ComputerDigest — SEPTEMBER 1936 



COMPUTER PRODUCTS 

For more details use the free information card inside the back cover 




CIRCLE 18 ON FREE INFORMATION CARD 



UNIVERSAL INTERFACE, the mode! 
488-2000, is a GPIB-488 interface for all 
IBM PC, IBM XT, IBM AT, IBM CLONES, 
Apple Macintosh, Tandy 3000, 2000, 
1200HD, and 1000. It can be used with 
any computer twins RS232, and with 
any language having access to RS232 
port (BASIC, Pascal, C). It can also be 
used with assembler or machine code. 

The baud rate is 300, 600, 1200, 
2400, 4800, and 9600; size is 7.5" x 
2.25" x 5", and the power require- 
ments are 105-125 volts AC, 60 Hz. 

The model 488-200 is priced at 
$675 .00. — Scientific Engineering 
Laboratories, Inc., 104 Charles Street, 
Suite 143, Boston, MA 02114. 




CIRCLE 19 ON FREE INFORMATION CARD 

PATCH & MONITOR MODULE, the 

model 9179 allows the user to monitor 
signals at the high-speed data inter- 
face and reconfigure the 
interconnection between modems 
and terminals when equipment mal- 
function occurs or data-path re-routing 
is required. 

The model 9779 V35 module is 
connected in series between each 
V35 modem and its associated data- 
terminal equipment. When switched 
to normal, the modem and terminal are 
connected together, and their interface 
signals are accessible at a front-panel 
connector for monitoring by a data-link 
analyzer If equipment malfunction is 
detected, the module may be switch- 
ed to its patch mode. When switched 
to patch, the modem and terminal 
connection is broken and all signals 
are routed to the front-panel con- 



nectors, thereby allowing a patch 
connection to back-up equipment 
while repairs are being made. Up to 
four modules slide into a standard 19" 
module rack. Delivery is from stock. 

The model 9179 is priced at 
$229 00 — Electro Standards Labo- 
ratory, Inc., PO Box 9144, Providence, 
Rl 02940. 

XT-COMPATIBLE COMPUTER, has all 

the features of an IBM PC/XT, such as: 
25 6K RAM memory 8 full expansion 
slots, 135-watt power supply floppy- 
disk controller board— up to 4 drives, 
full-function keyboard, 360KB 48TPI 
floppy-disk drive, high-resolution 
monochrome monitor, monochrome 




CIRCLE SO ON FREE INFORMATION CARD 



graphics card w/printer port, and BIOS 
compatible with IBM PO XT. The 
complete system is FCC-approved. 

Many add-on options are available, 
such as 640KB mother board; 10, 20, 
and 40 MB disks,- RGB monitors,- tape 
back-up systems; color graphics 
board; hard-disk controller board, and 
color monitors. The price of the com- 
plete system (not including add-ons) 
is $999.00— Sintec Company, 28 
Eighth St., Box 410, Frenchtown, NJ 
08825. 

FINANCIAL PLANNER, is the Com- 
modore 128 computer version of 
"Sylvia Porter's Personal Financial Plan- 
ner." The user is taken step-by-step 
through a series of questions that will 
help him or her develop comprehen- 
sive plans to determine the best 
financial moves for his or her career, 
marital status, savings, life insurance, 



TflKUI0*3 



SYLVIA IV)RTICRS 
IVKSONAI. ITVYVi 

128" 




CIRCLE 21 ON FREE INFORMATION CARD 



investments, life style, retirement, and 
estate. The user can also plan ahead 
for protection against major medical 
expenses, prolonged disability and 
other possible adversities. 

The program also includes elec- 
tronic checkbook and checkwriting, 
budget preparation, tax aids, financial- 
statement preparation, and financial- 
inventory tracking. 

The suggested retail price for the 
Financial Planner is $129.95 for the IBM; 
$99.95 for Apple: $69.95 for the Com- 
modore 128, and $59.95 for the 
Commodore 64. — Timeworks, 444 
Lake Cook Road, Deerfield, IL 60015. 

LIGHT PEN, the Feather, is cordless, 

fully self-contained, and lightweight. 
Typical uses include rapid data-entry 
and retrieval in medical settings, CAD 




CIRCLE M ON FREE INFORMATION CARD 

design of a new mechanical part, and 
high-speed manipulaiton of business 
spread-sheets. It uses an infra-red 
communications link, powered by 
commonly available batteries. 

The Feather is priced at $195.00.— 
Hei, Inc., Victoria, MN 55386. 



September 1986 — Computer Dig est 5 



SOFTWARE REVIEW 



MINI-JINI—A record keeper for the Commodore 64. 



■There are probably more 64's in use than any other 
personal computer: It's difficult to say how many but 
depend on it, the numbers dre really up there. Mostly, 
it's used for games because the software required for 
business applications is beyond the convenience or 
capability of the 64's slow cassette and disk storage 
systems. If used with software that allows and 
compensates for this slowness, the 64 can be a 
sparkling performer Such a programis" MINI JIN1, an in- 
memory record keeping system attractive to hobbyists, 
technicians and small service shops because it's easy to 
use, easy to set up and provides a convenient way to 
computerize a modest-size customer file or inventory 
mailing list or just substitute for a 3 x 5 file card index. 
It's extremely versatile. 

MINI JINI is a data filing system that organizes data 
into customized reports. The program stores related 
data in individual records, each consisting of a list of 
up to ten related items called "fields" such as name, 
date, telephone, etc. A field can have any kind of 
format or content, as long as several characters 
required by the program itself aren't used, such as the 
comma, colon or quotation mark. One of the fields can 
even store data created from other fields through an 
internal function called MATH PACK, which performs 
calculations on the whole file, letting the user add, 
subtract, multiply or divide two fields or a field and a 
constant. MathPack functions include: Add a constant, 
add two fields, subtract a constant, subtract two fields, 
multiply a constant, multiply two fields, divide a 
constant, divide two fields, sum and average. 

While each record can be 800 characters, an 
individual field length is limited to two complete lines 
(80 characters), and unused characters in one field 
cannot be used in another field. 80 characters is the 
absolute maximum for any field. Since all data is within 
the RAM the total number of records per file depends 
on the individual record size(s). If a data file gets too 
large for the 64's RAM it must be split and stored on 
cassette or disk as two separate files. 

As each record is entered into RAM, MINI JINI 
assigns a sequential number which is not used unless 
changing or deleting a record. If a record is deleted, 
the program closes the gap, renumbers the records, 
and frees the RAM for other records. 



The entire file can be scanned to view data. Specific 
data can be found through GLOBAf SEARCH through 
the entire database, or FIELD SEARCH which looks 
through a specified field. The actual search is rapid 
because the entire database exists in memory and 
nothing is faster than reading RAM. To view or print 
data in a specified sequence, records can be 
alphabetized in ASCII for any given field: For example, 
a file might be ordered by customer's last name, by 
Zip, or by the date on which you last serviced. 

Unlimited updating is possible simply by overtyping 
the screen display When this is entered as a "changed 
record," it substitutes for the RAM record. It is likewise 
possible to selectively delete data for a particular field 
or the entire record. 

The PRINT FILE mode provides hardcopy for a record 
or up to four lines from any user-selected fields on 
standard ls /i6 inch mailing labels. And fields can be 
printed in any desired order 

A WRITE-A-FILE mode writes data to tape, disk or a 
printer, even a modem with the correct modem hard 
and software, A READ mode, similarly, reads data from 
tape or disk. 

MINI JINI is supplied as a ROM cartridge that 
resembles and works like a standard game cartridge. 
Just plug it in and the program comes up running with 
a logo that changes to a menu. All functions and 
operating modes including an initial selection of screen 
colors are menu driven and all modes provide a means 
for returning to main menu should something go wrong 
or if you change your mind. No entries become 
permanent until entered by the user 

MINI JINI is not in the same class as a sophisticated 
data-management system with unlimited storage 
capacity and reporting formats. It does provide a way 
to store and access moderate amounts of information. 
Keep in mind that loading data from tape or disk still 
takes time. It required almost six minutes to load a file 
of 85 ten-field records. The program runs fast only 
when the data is in RAM, not when loading or 
unloading. 

MINI JINI is sold by JINI Micro Systems, Inc., Box 
274, Riverdale, NY 10463.^(D^ 

CIRCLE 17 ON FREE INFORMATION CARD 



6 ComputerDigest — SEPTEMBER 1 986 



COMPUTER 
CB SCANNER 



How to use your computer 
to scan the CB channels 



Dr. Frank P. Maloney 



■Although the CB craze seems to be over; there 
continues to be a sreat deal of activity on the channels. 
In fact, now that the first rush has passed, activity 
seems to have become more serious. Fire up your 
transceiver, and you'll find social groups using the 
inexpensive conference-call, REACT on channel 9, your 
neighborhood townwatch, security at civic and sports 
events, hobbyists, local paging, and of course, the 
channel 19 circus. While your interest may be piqued, I 
suspect that you will soon rediscover why you 
abandoned CB in the first place. We grow weary of 
constantly flipping that 40-channel switch looking. 

Use the computer 

How much more convenient it would be if, using a 
home computer, we could directly access any channel 
from the computer's keyboard, or step through the 
channels one-at-a-time, or rapidly display the activity 
on all 40 channels (like an oscilloscope) or even scan a 
pre-set group of channels, stopping on one of them 
when there is activity (like a scanner)? If you have a 
recently-manufactured CB that uses a phase-locked 




THE COMPLETE CIRCUIT, ready for installation and use. Wire 
wrap techniques were used by author, on pert board. 

loop integrated circuit (PLL IC) synthesizer instead of 
individual crystals, and a home computer, the above 
features are simple to implement. And if yours is a 
Commodore C64, SX64 or C128 computer, the 
programs are already written for you. 

Locate the schematic diagram of your CB transceiver, 
or open the unit up and take a look around. Make sure 
you disconnect it from the power source first. Near the 
40-channel selector switch, will be the PLL IC. Chances 
will be good that it is a type LC7131, used in many 
Cobra and Radio Shack units. Should it not be a 7131, 
don't worry Although I will be describing the 7131, the 
basic principles are the same for all PLL IC's. 

Note that there are six lines going from the selector 
switch to pins 1 through 6 of the 7131 chip. These lines 
contain the binary-coded decimal (BCD) value of the 
channel number, and hold the unit's digit, lines 5 and 6 
hold the tens digit. As an example, channel 23 is 
coded; 

PIN 654321 : DATA 10:0011 : CHANNEL 2: 3 

Channel 40 is an exception, it is coded all zeroes. A 
data 1 means about 9 volts on that pin, a data zero is 



SEPTEMBER 1986 — ComputerDigest 7 



about volts. So there is the plan, set the selector 
switch to channel 40, and have a home computer's 
peripheral port control these lines to select the desired 
channel. Then have the computer "read" the S-meter 
with the same paddle port. Any home computer will 
do, as Ions as it has a peripheral port and a same port 
that you can control. 

Other chips? 

If you found other chips than the 7131, such as the 
UPD2824 or the LC7132 used in some Radio Shack units, 
you're still in business. The 2824 is almost identical to 
the 7131. The 7132 uses 8 lines instead of 6 to control 
the channel, so the codins will be different from what I 
have previously described. Spend a few minutes with 
a voltmeter, and by changing the selector switch -while 
you test pin voltages, you can figure out the coding for 
most any PLL IC. 

Look at interface circuit, Fig. 1., showing the 
optocoupling to pins 1 through 6 on the 7131 PLL IC. A 
data zero on the cathode of optocoupler OC1 allows 



COMMODORE USER 
I/O PORT 



GROUND PIN A 



+5 



PBO 



'(IV A — I 

GVIwFJfc 

2 —L- rrT> 



R 1,470 n 



0C1 
4N28[4 



R2.4T0O 



FBI 




DC2 
4N2B 




-a: 



R3470ft 
1 



nc3 

4N28 



P83 



-~1 



R4.470O 



0C4 
4N2S 



PE4 



IE- 



RE, 470O 
1 



0C5 
4N2B 



2 
1 



I KM 



DCS 
4N2B 



PBS 



-T r- 



FIG. 1— SCHEMATIC DIAGRAM of the interface circuit, linking 
the computer's peripheral port to the PLL IC in a CB trans- 
ceiver. 



COMMODORE 
GAME PORT 1 



-MA— 1 r 



R0 
50KS1 



/77 



"-© 



-N- 



-) . {^ — PIH3 

7 



0C7 



CASE 




va- 



cs^ 



FINAL IF 
TRANSFORMER 



I 



C3 



B 




EXISTING CBS-METER CIRCUIT 



VA- 

CALIBRATE 



S-METER 



m 



FIG. 2— S-METER buffer amplifier interface circuit is shown 
here schematically. 

current to flow from the + 5 volt supply from the 
computer into the peripheral port (PBO on the 
Commodore). That turns the transistor on, allowing 
current to flow from pin 18 to pin 1 of the PLL IC, 
placing a data 1 there. The 6 optocouplers are required 
to isolate the computer's from the transistor's differing 
voltages, as well as to prevent the RF hash from the 
computer from interferring with CB reception. Even so, 
be sure to use shielded cable from the peripheral port 
to the optocouplers, as shown in the schematic. 

The S-meter level is communicated to the 
computer's game paddle input by a simple 741 op- 
amp and another optocoupiec The circuit is shown in 
F13. 2. A typical S-meter circuit consists of a diode 
detector on the final IF transformer; and a smoothing 




THE COMPUTER MONITOR, showing display of activity plot- 
ted vertically on the 40 channels. Observe the bleed-over on 
channel 8 to adjacent channels caused by over modulation. 



8 ComputerDigest — SEPTEMBER 1986 




VERTICAL PLOT OF ACTIVITY ON CHANNEL 15 plotted as a 
function of time (horizontal). A transmitter has just keyed up. 
Notice the overshoot of the receiver's automatic gain control 
(AGC). 

filter, R and C. The attack time constant is T = RC 
seconds (without C2). We sample the voltage V on C 
with the op-amp, which forces a current i = V/Rg 
through the optocoupler diode. Thus, trimpot Rg sets 
the gain of the circuit. Offset current is provided by 
trimpot Ro, These gain and offset levels will be set later 
so the range 51 through S9 + 30 dB on your S-meter 
results in the correct display range on your computer: 
Also, C2 must be chosen so that T is about twice as 
long as the digitization speed of the computer's 
paddle port. For the Commodore, a reading is 
completed every 512 phase-two cycles, about 0.0005 
second. So choose C2 so that T = RC + C2) = 0.001 
second. If you cannot determine R and C for your CB, a 
good value to try is 1 microfarad. The resulting current 
through the optocoupler diode varies the resistance 
between the collector and the emitter of the transistor, 
functioning like a variuable resistance paddle. That 
resistance is digitized by the computer. 

The cost of these materials is less than $15., 
depending on how fancy an enclosure you buy you 
can use simple point-to-point wiring on perf board. 
Wire wrap is particularly easy with the IC socket pins, 
and these can be tack-soldered to the foil side of your 
CB. you can tap the S-meter voltage between C and 






ACTIVITY PLOTTED VERTICALLY on channel 10 against time 
(horizontal). A distant transmitter is seen fading in and out, 
indicating poor skip conditions. 



SCANNER OPERATION. Channels 9, 19, and 31-35 have been 
programmed. Channel 33 was last active, but has timed out. 
Channel 9 is presently being monitored. 

transceiver ground, from the C-side of R or the calibrate 

trimpot. 

PARTS LIST 

Semiconductors 

OC1 - OC7— 4N28 Optocouplers 
IC1— 741 Op-Amp 

Resistors 

(All resistors 14 watt, 10% unless otherwise specified) 

R1 - R6 — 470 ohms 

Rg— 1000 ohm gain trimpot 

Ro— 50.000 ohm offset trimpot 

Capacitors 

CI, C3— 1jaF ceramic. 50V 

C2— See text 

Miscellaneous 

B1, B2— 9-voit batteries 

S1— DPST or DPDT switch 

24-pin female edge connector for Commodore l<0 port, 9-pin 
DB9 female connector for Commodore game l f O port, 
enclosure, shielded microphone cable, IC sockets. 

The software 

Once you have the circuit working poroperly you 
will need to work on the software. Initially, you can use 
simple POKE'S and PEEK'S from BASIC to see if the 
coding for the PLL IC is correct. A complete program 
should enable to you to: 

-directly access any channel by using the keyboard 
digits 

-step up or down a channel at a time 
-display the activity on any all 40 channels 
-display in oscilloscope fashion, the activity on a 
channel 

-scan a programmable set of channels, stopping to 
monitor whenever the activity exceeds a threshold. 

If you have a Commodore computer and wish to 
avoid re-inventing the wheel, I can send you a machine 
language routine which implements the above 
functions. Just send a new, foimatted but otherwise 
blank diskette with your name and address on the disk 
and a sturdy stamped, self-addressed envelope to: Dr 
F. P Maloney Department of Astronomy and 
Astrophysics, Vilannova University Villanova, PA 19085. 
The disk and full operating instructions will be returned 
to you.-^tD^ 



SEPTEMBER 1986 — ComputerDigest 9 



Electronics Paperback Books 

EVERY BOOK IN THIS AD $5 OR LESS! 







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X 




fist 




I BP125— 25 SIMPLE AMATEUR BAND ANTENNAS,.,.,S5.D0. All are inexpensive 

to build, yet perform well. Diodes, beams, triable and even a mini rhombic, 

r; BP 12B-20 PROGRAMS FOR THE ZX SPECTRUM & 16K ZXB1 $5.00. Pro- 
grams to run. Programs to have lun wilh. Even programs Ihal will help you learn to 
write programs. 

f J 160— COIL DESIGN & CONSTRUCTION MANUAL $5.00. How Ihe hobbyist 

can build RF r IF. audio and power coils, chokes and transformers. Covers AM, FM 

and TV applications. 

D 209— PRACTICAL STEREO i QUADROPHONV HANDBOOK S3-00- A refer- 
ence book for all interested tn stereo and multichannel sound reproduction. 

H 214— AUDIO ENTHUSIAST'S HANDBOOK $3.5(K Explains recordrplayback 

curves, stylus compliance, how we evaluate loudness, how compatible is compati- 
ble, and more 

: ] 219— SOLID-STATE NOVELTY PRQJECTS.....S3.S0. Fun projects include Ihe 
Oplomin, a musical instrument Ihal is played by reflecting, a light beam with your 
hand, and many more. 

H 222— SOLID STATE SHORT WAVE RECEIVERS FOR BEGINNERS $4,50, 

Modem solid-stale circuits thai will deliver a (airly high level of performance. 

D BP126— BASIC & PASCAL IN PARALLEL S4,Z5. Takes these two program- 
ming languages and develops programs in both languages simultaneously. 

n 224 — 50 CMOS IC PROJECTS $4.50. Includes sections on multivibrators. 

amplifiers and osciltators, trigger devices, and special devices. 

D 225— A PRACTICAL INTRODUCTION TO DIGITAL IC'S $4.25. Mainly con- 
cerned with TTL devices. Includes several $imple projects ptus a logic circuit test 
set and a digital counler timer. 

□ 226— HOW TO BUILD ADVANCED SHORT WAVE RECEIVERS $5.00. Full 

practical construction details ol a number of receivers are presented. 

R 227— BEGINNERS GUIDE TO BUILDING ELECTRONIC PROJECTS $5,00. 

How to tackle the practical side ol electronics so you can successfully build 
electronic projects. 

□ BP6— ENGINEERS AND MACHINISTS REFERENCE TABLES $2,00- Screw 

Ihreati data, drill sizes, circle division, angles, tapers and more, 

H 123— FIRST BOOK OF PRACTICAL ELECTRONIC PROJECTS $3.75. Proj- 
ects include audio distortion meter, super FET receiver, guilar amplifier, metronome 
and more. 

M BP24— 52 PROJECTS USING IC 741 54,00, Lots of projects built around this 

one available IC 

U BP32— HOW TO BUILD YOUR OWN METAL & TREASURE LO- 
CATORS $5,00. Electronic and practical details on the simple and inexpensive 

construction of hetrodyne melal locators. 



□ BP33— ELECTRONIC CALCULATOR USERS HANDBOOK,,.. $5.00, Invaluable 
book lor all calculator owners. Tells how to get Ihe most out of your calculator. 



; BP3B— 50 CIRCUITS USING GERMANIUM, SILICON & ZENER DI- 
ODES $3,75. A collection of useful circuits you'll wan! in your library. 



G BP37— 50 PROJECTS USING RELAYS, SCRS & TRIACS $5-00, Build pri- 
ority indicators, light modulators, warning devices, light dimmers and more. 



I BP39— SO FET TRANSISTOR PROJECTS $4.50. RF ampliliers, lest equip- 
ment, tuners, receivers, lone controls, etc. 



D BP42— SIMPLE LED CIRCUITS $4.25, A large selection of simple applications 

for this simple electronic component 



LJ BP43— HOW TO MAKE WALKEE TALKIES $5.00. Equipment for low-power 

hand-held or portable operation. 



Q BP45— PROJECTS IN OPTOELECTRONICS $5.00. Includes inlra-red detec- 
tors, transmitters, modulated light transmission and photographic applications. 



I ] BP48— ELECTRONIC PROJECTS FOR BEGINNERS $5.00, A wide range ol 

easily completed projects for the beginner. Includes some no-soldering projects, 

I I BP49— POPULAR ELECTRONIC PROJECTS $4.75. Radio, audio, househoid 

and test equipment projects are all included. 

n BP51— ELECTRONIC MUSIC AND CREATIVE TAPE RECORDING $5.00. 

Shows how you can make electronic music al home wilh the simplest and most 
inexpensive equipment. 

: i BPS6— ELECTRONIC SECURITY DEVICES $5.00. Includes both simple and 

more sophisticated burglar alarm circuits using light, inlra-red. and ultrasonics. 

! ! BP59— SECOND BOOK OF CMOS IC PROJECTS $4.25. More circuits show- 
ing CMOS applications. Most are of a fairly simple design. 

I. ! BP72— A MICROPROCESSOR PRIMER $4.50. We start by designing a small 

computer and show how we can overcome its shortcomings. 

[ I BP7B— PRACTICAL COMPUTER EXPERIMENTS .....$4.50. Construct typical 
computer circuits using descrel logic to form a basic understanding ol how compuF 

ers fund ion. 

D BP91— AN INTRODUCTION TO RADIO DXING $500. How you can tune in on 

those amateur and commercial broadcasts from around the world in the comfort of 
your home, 

; ] BP94— ELECTRONIC PROJECTS FOR CARS AND BOATS $5.00, Fifteen 

simple projects Ihal you can use wilh your car or boal. AJI are designed to operate 
from 12-voJt DC supplies. 




RET 



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10 ComputerDigest — SEPTEMBER 1986 



SOUP-UP 

your pc 



Add punch to your IBM PC. 

T J Byers 

*While it is rumored that the new super- 
microprocessor chips, such as Intel's 80386, are going 
to revolutionize the personal computer, some think 
there is more than enough power in the architecture of 
the popular 8086 microprocessor to keep the 
computer industry satisfied for some time to come. 

In the wake of claims for chips with mainframe 
power, NEC Electronics has taken the venerable 8086 
and given it more punch. The new design, the V30, 
promises to improve system performance by 25 to 30 
percent. And, this achieved inside the chip so no 
changes to the computer system are required. 

Microprocessor architecture 

The secret to this turbocharged performance lies in 
the architecture of the new chip. Unlike the 8086, 
which uses a single 16-bit internal bus, the NEC 
microprocessor uses an advanced interface controller 
that feeds two internal buses. Fewer ticks of the clock 
process the data as operations can be divided into 
two groups and run simultaneously 

To understand how, we must learn how 
microprocessors work. The microprocessor is divided 
into five sections, as illustrated in Fig, 1. Each division 
performs a function that affects the operation of 
another part of the internal microprocessor system. 

First is the I/O interface bus, which stands between 
the internal structure of the chip and the outside world. 
It translates incoming and outgoing signals into voltages 
that are compatible with both sides of the system. 

Steering the I/O interface is a bus interface controller. 
This is the traffic cop It tells the data which way to go 
and when. The bus interface controller contains five 
on-board memory cells called registers. Each register 
holds 16 bits of user- inputted binary data used to 
coordinate the operations of the controller. 

Beyond the bus interface controller is the 
microprocessor itself. It is composed of three parts: a 
microcode ROM (Read-Only Memory), an arithmetic 
logic unit (ALU), and the data registers. 

Processing data through the microprocessor consists 
of entering the data into one or more of the data 
registers and performing an operation on it. The ALU is 
the engine which manipulates the data. Coordinating 
the effort is the microcode ROM. 

If we have two numbers that we wish to add, we 
begin by tellins the microprocessor that the next 



operation will be addition. The ROM looks up a table 
that contains all the instructions necessary to derive the 
sum of two numbers. These are the microcodes. For 
addition, three microcode instructions are needed. The 
process goes something like this. 

First, fetch the number from register A, pass it 
through the internal bus, and place it in the ALU. 
Second, fetch the number from register B, pass it 
through the internal bus, and place it in the ALU. Third, 
add the two together and place the sum in register A 
using the internal bus. Each instruction requires one tick 
of the clock. If a clock pulse occurs every 
microsecond, it will take three microseconds to tally 
the two numbers. Multiplication and division are much 
more complicated because more steps are involved. 
To multiply a number by 10, for example, the base 
number must be added to the sum ten times. It is not 
uncommon to see functions requiring hundreds of 
microcoded instructions. Remember, each instruction 
uses one clock cycle, and the longer the microcode, 
the longer it takes to execute the command. 

Take the "A" bus 

Each instruction of our example used the internal bus 
for part of its operation. This is not unusual. In fact, 
most microcode instructions make use of the internal 



MAIN 

DATA 

BUS 



REGISTERS 



c 



ARITHMETIC 
LOGIC 
UNIT 



^> 



MICROCODE 
ROM 



BUS 
INTERFACE 

CONTROLLER 







JX 



^3 



I/O INTERFACE 



V 



Fig. 1— THE 8086/8088 MICROPROCESSOR is divided into 
five sections. Each division performs a function that controls 
or affects the operation of another part of the internal micro- 
processor system. Data within the chip is passed from func- 
tion to function through a single 16-bit wide main data bus. 



SEPTEMBER 1986 — ComputerDigest 11 



bus in one way or another 

The internal bus is the data link between the 
elements of the processor Before bus technology all 
data was treated serially, with each bit passing through 
each element one bit at a time. The bus allows data to 
be routed in parallel, which improves throughput. 

Unfortunately, the bus can pass only so much data at 
a time, depending on its width. If the bus is 8-bits 
wide, then it can transfer a byte at a time. A 16-bit bus 
can pass two bytes, etc, Designers realized that to get 
more done, the bus would have to be made wider, 
and current trends are towards a 32-bit bus, such as 
the one Intel is developing for its 80386 super- 
computer chip. 

Present day personal computers, however, use either 
an 8-bit or 16-bit bus, so a major redesign is necessary 
before the new 32-bit microprocessors can be used. 



C 






MAIN 
DATA 
BUS 



REGISTERS 



c 






TEMPORARY 

REGISTER 

SHIF 




RARY A K 



ARITHMETIC 
LOGIC 
UNIT 



-J 



MICROCODE 
ROM 



BUS 

INTERFACE 

CONTROLLER 



^ 



=0= 



<^> 



I/O INTERFACE 



Fig. 2— IN THE DUAL BUS METHOD, such as supported by 
NEC's V20 and V30, there is a main data bus and a subdata 
bus. Data is passed through the main bus for all main input 
and output operations. Concurrently, internally-routed data 
may be passed through the subdata bus, thus improving data 
throughput. 



Add the "B" bus 

There is another way to do more. We can leave the 
bus as is and add a second internal bus to the 
structure. This is what NEC has done in the V30. 

In the dual-bus method, there is a main data bus and 
a subdata bus, as outlined in Fig. 2. Data is passed 
through the main bus according to the needs of the 
microprocessor: In addition, data may be concurrently 
passed through the subdata bus in a similar fashion. 
The result is a greater throughput of data. 

Let's refer to our previous example. Like the single 
bus method, the microcode ROM contains the 
instructions for the operation- — addition. This time, only 
two instructions are necessary to derive the sum of two 
numbers. It goes as follows. 

First, the number contained in register A is passed to 
the ALU through the main data bus. At the same time, 
the number contained in register B is passed through 
the subdata bus and loaded into the ALU. This 
operation requires one microcode instruction, and one 
tick of the clock. Second, the numbers are summed 
and the result is passed through the main data bus to 
register A. The entire process takes two clock cycles. 

We have increased the speed of the microprocessor 
by 33 percent, without modification to the clock or the 
external I/O interface. The new chip is compatible with 
the old chip. All modifications to the system are 
internal and not apparent to the user or the computer 
system. 

A new chip in an old package 

If this was all NEC did to enhance the 8086, it would 
still be a significant improvement. But since the internal 
architecture was being redesigned anyway it wasn't 
that difficult for NEC to enhance it further. 

To further improve performance, NEC added two 
temporary shift registers to the internal structure. Each 
register is 16-bits wide. These registers are attached 
directly to the ALU and actually become an extension 
of the ALU. Whencascaded, these registers serve as 
immediate data storage that provides speedier 
multiplication and division operations because the data 
doesn't have to travel through the data bus but twice: 
Once to load the registers and once to unload them. 

The second register, when split from the first, can be 
used to hasten shift and rotate functions. The register is 
actually a part of the ALU, and fewer microcode 
commands are required per function. And, NEC added 
a loop counter to the ALU that keeps track of repeat 
instructions for rotate and shift so they don't have to 
be constantly inputted from the microcode ROM. 

NEC also added an Effective Address Generator 
(EAG) to the V30. This performs high-speed processing 
of memory locations for memory accessing. Calculating 
by the microcode method normally requires 5 to 12 
clock cycles. The EAG generates effective addresses 
using hardware and needs only two clock cycles. A 
program counter and a prefetch pointer offer more 
efficient use of the branch, call, return, and break 
operations by keeping track of current and future 
program addresses. 

The entire procedure requires nearly twice as many 



12 ComputerDigest — SEPTEMBER 1986 



transistors as the original microprocessor. This approach 
is necessary however, if the new architecture is to be 
externally compatible with existins designs. 

Improved instruction set 

Complete compatibility between the 8086 and V30 
is, of course, essential to the V30's success. And the 
same qualifications apply to the software. NEC 
duplicates the entire 8086 instruction set. To take full 
advantage of the hardware improvements, they found it 
necessary to enhance 16 of the original instructions and 
add 14 brand new ones. 

Enhancements are made to the SHIR (SH) and 
ROTATE CRO) instructions, as well as the MULTIPLY 
(MUL) command, to take advantage of the new 
temporary shift registers attached to the ALU. PUSH 
and POP are enhanced to deal with 8 general registers 
at once and there are changes in the way the chip 
deals with block memory and block I/O instructions. A 
list of enhancements is shown in Fig. 3. 

In addition to the 8086 instructions and the 
enhanced instructions, the V30 also contains the 
following unique instructions. 

Two instructions are used for variable length bit field 
operations. These are effective for dealing with packed 
arrays found in screen graphics and higher-level 
languages, like PASCAL. Another group of instructions 
manages packed BCD (binary coded decimal) data as 
strings or byte -formatted operands. The third group 
deals with the manipulation of specific data bits within 
data registers or memory locations. A breakdown of 
the new instruction set is outlined in Fig. 4. 

Starting a family 

NEC is offering two enhanced versions of the 8086 
microprocessor The first, an 8-bit external bus 
microprocessor that NEC affectionately calls the WO, is 
the electrical and logical equivalent of the 8088. The 









ENHANCED INSTRUCTIONS 
Function 

Pushes immediate data onto stack 
Pushes 8 general registers onto stack 
Pops 8 general registers from stack 
Executes 16-bit multiply of register or 

memory contents by immediate data 
Shifts/rotates register or memory by SHR 

imm8 immediate value 



Instruction 

PUSH imm 
PUSH R 
POPR 
MUL imm 

SHL imm8 

SHRA imm8 

ROL imm8 

ROR imm8 

ROLC imm8 

RORC imm8 

CHKIND Checks array index against set 

boundaries 
INM Moves a string from an I/O port to 

memory 
OUTM Moves a string from memory to an I/O 

port 
PREPARE Allocates an area for a stack frame and 

copies previous frame pointers 
DISPOSE Frees the current stack frame on a 

procedure exit 

Fig. 3— THE ABOVE INSTRUCTIONS have been enhanced 
from the 8086.8088 instruction set as indicated. 



NEW INSTRUCTIONS 
Instruction Function 

INS Insert bit field 

EXT Extract bit field 

ADD4S Adds packed decimal strings 

SUB4S Subtract packed decimal string 

CMP4S Compares two packed decimal strings 

ROL4 Rotates one BCD digit left through AL 

ROR4 Rotates one BCD digit right through AL 

TEST1 Tests a specific bit and sets Z flag 

NOT1 Inverts a specific bit 

CLR1 Clears a specific bit 

SET1 Sets a specific bit 

REPC Repeats next instruction until CY is clear 

REPNC Repeats next instruction until CY is set 

FP02 Additional floating point processor call 

Fig.4— THE INSTRUCTIONS ABOVE are new to the 8086/8088 
instruction set. Altogether, there are 14 new Instructions di- 
vided into three categories: variable length bit field opera- 
tions, packed BCD operations, and bit manipulation 
instructions. 

second, the V30, duplicates the 8086 with its 16-bit 
external bus structure. Both use 16-bit internal buses 
and both are hardware and software replacements for 
their counterparts. 

Things are moving fast, and the computer of the 
future will be something to behold. It is reassuring to 
know, though, that companies like NEC are doing their 
best to keep existing technology current. 

If you ever wanted to feel the acceleration of a 
turbocharged machine, now is your chance. The NEC 
W0 offers the perfect opportunity for IBM PC and PC 
compatible owners to upgrade for a fraction the cost 
of a turbo board. To begin, remove your old 8088 
microprocessor chip and replace it with a WO to gain 
both speed and expanded programming capabilities. 
The chips are pin-for-pin compatible and no software 
or hardware adjustments are required. 

To install the new chip you remove the five 1/4-inch 
screws securing the cover to the back panel and 
sliding the cover forward. Locate the 8088 
microprocessor chip. It is at the rear, ahead of the 
cassette connector 

Make sure you are free of static electricity before 
proceeding. A good precaution is to touch your hands 
to the metal chassis before working. Gently remove the 
8088 from its socket using a chip puller 

Insert the new chip by aligning its legs with the 
socket pins (locating notch facing the rear apron) and 
firmly push into place. Replace the cover 

This $30 chip won't transform your PC into an AT. But 
it will improve overall performance by 10 to 20 
percent. This is just the tip of the iceberg. The real 
impact of the upgrade will be realized when software 
houses start incorporating the new instruction set in 
their products. Meanwhile, enjoy the benefits of 
tomorrow's technology 

NOTE: if you are having trouble locating a V20 
processor contact Westpro Data Sources at 21704 
Golden Triangle Road, Saugus, CA 91350. They will ship 
you a V20 for $30 ppd. Other V-series chips are also 
available; contact Westpro for price and 
availability-^D^- 



SEPTEMBER 1986 — ComputerDigest 13 



OPTICAL DISKS 

Soon you may be "playing" Compact Disks on your computer! 
Marc Stern 



■Do you remember when laser disk players were the 
rage? It was a short time ago they were supposed to 
sweep the video field. It never happened and they 
faded from that picture temporarily Well, they're back, 
but their name and use has changed radically 

Instead of creating TV images, they are creating 
sounds heard in compact disk audio players and are 
beginning to appear as read-only storage devices in 
microcomputers. And instead of being called laser 
video disks, they're now called compact audio disks, 
or, in the computer world, optical storage disks, 
compact disks or compact-disk-read-only memory 
(CD-ROM). 

When you think about it, using a laser-created optical 
disk for storage makes sense. 

Unlike magnetic media where data are recorded via 
frequency modulation, optical disks are created as a 
laser-through burn in tiny sections of substrate within 
the disk. The bum or lack of a bum determines if a 
digital 1 or has been recorded. Optical disks are 
instantly digital. 




FIG 1— ORGANIZED IN CONCENTRIC RINGS, the outer sec- 
tors of a standard disk are recorded using constant angular 
velocity where the outer sectors are physically larger than the 
inner sectors of a disk. Each track is made up of a specific 
number of sectors and the size differential is due to the fact 
that the speed of the outer rim of the disk seems greater than 
that of the inner areas. To keep things equal, the size of the 
outer sectors increases because of the increased apparent 
speed. 



Advantages 

The most obvious advantage of an optical disk is its 
permanence. Like a compact audio disk, data are 
recorded and encased within a compact disk's plastic 
shell and can't be changed or erased. On a floppy or 
hard disk, coated with magnetic media, stray magnetic 
fields, heat, cold, dust or smoke may cause data to be 
corrupted. Floppy or hard disks can at best be thought 
of as temporary long-term storage, while optical disks 
can be thought of as long-term, permanent storage. 

The most-obvious advantage of an 
optical disk is its permanence. 
Optical disks are impervious to 
damage. Since the optical disk's 
recording surface is in a plastic 
layer or shell, it can be 
manhandled. 



Optical disks are impervious to damage. If you've 
worked with microcomputers you know the caveats of 
disk handling, watching out for fingerprints,* dust; 
cigarette smoke, and the like. Since the optical disk's 
recording surface is in a plastic layer or shell, it can be 
manhandled. Fingerprints won't harm the data surface 
and neither will dust, cigarette smoke or magnetic 
fields. 

From a storage standpoint, the key to an optical disk 
is data density Rather than just storing 10 megabytes or 
20 megabytes, as is now commonly done on personal 
computer hard disks, optical disks are capable of 
storing from 200 megabytes to 1 gigabyte of data. As 
an analogy think of storing the entire "Encyclopaedia 
Brittanica" in your microcomputer. It will take several 
hard disks or many boxes of floppies. In contrast, you 
can easily store it on one optical disk and still have 
some room left over. 

An optical disk's biggest storage disadvantage is its 
one -write nature. After it has been filled once, nothing 
can be added. Research has been conducted for the 
last several years in an effort to make optical disks read- 
and-write devices, but it still hasn't paid off to any 
cost-effective degree. 



14 ComputerDigest — SEPTEMBER 1986 



In a way optical disk technology is perhaps the 
ultimate solution to computer compatibility In the 
floppy and hard disk world, PC/MS-DOS has offered a 
measure of compatibility among differing systems. 
However, since there is only one major standard for 
optical disks, developed by Phillips and Sony optical 
disks for one microcomputer system should work on 
another 

The impetus to this standard, by the way, was the 
digital audio standard developed for compact disk 
players by the two electronics giants. 

Differences 

Up to now, we've explored the chief differences 
between traditional magnetic disk technology and 
optical disk technology Now let's look at the more 
technical issues that explain other differences. 

Foremost among the technical differences is the 
format of the surface of the disk. Like a traditional disk, 
the optical disk has tracks and sectors, but, unlike the 
traditional disk, it uses a different physical format. 

Traditional disk technology defines its format using 
constant angular velocity To explain, take a close look 
at Fig. 1 and you'll see that the data sectors toward the 
center of the disk are smaller than those at the rim 
where the circumference is greater and the disk's 
relative linear speed also seems greater, with respect to 
the center Because of the seeming speed difference 
the physical size of the data sectors must be larger to 
keep sectors equal. Thus, angular velocity across the 
section of the disk is kept equal by the changing size 
factor of each sector 

An optical disk differs because the read head and 
the disk surface retain the same relative speed at all 
times. To do this, the disk's speed is changed as the 
read head moves across. This results in a spiral 
arrangement of data sectors, all having the same linear 
length because they're recorded at the same apparent 
speed. If you look closely at Fig. 2, you'll see that since 
data tracks spiral toward the rim, there are fewer data 




SECTORS 

FIG 2— WITH CONSTANT LINEAR VELOCITY, the read head 
and disk speed remain the same across the disk. The result is 
a series of tracks whose sectors are physically the same 
length but which appear spiral in shape. 



sectors on the center than at the edge. The ratio can 
vary by more than 2 to 1, or 9 sectors at the center and 
20 at the rim, per track. 

This complicates things on an optical disk because 
there are no fixed reference points. With constant 
angular velocity recording each track contains a fixed 
number of sectors. It is easy to find the location of a 
track and sector, if your system knows the starting track 
and sector address of a file. The read-write head 
moves ahead N locations to find it, once it knows the 
original address. 

Things are more complicated on an optical disk. 
With a surface of spiral tracks, try to find a specific 
location easily Because there is no fixed relationship 
between the an optical disk's track and the number of 
sectors on the track, the microcomputer has to go 
through a more complicated routine finding a location. 

Further complicating this is speeding up or slowing 
the disk's rotation so the speed of the head and disk 
remain constant. When these two factors are taken into 
consideration, accessing information is slower than 
other types of storage media. 

It's not uncommon for an average seek to take 500 
ms, while the worst case time approaches 1 second. 
This contrasts with average seek times in the 100 ms 
range for an average 10 megabyte hard disk and worst 
case times in the 200 ms range. Performance 
differences can also be seen in the fact that an optical 
disk's average latency is 100 ms, while it is only 8.3 ms 
for the fixed disk. 



Rather than storing 10 to 20 
megabytes as is done on PC hard 
disks, optical disks can store 200 
megabytes to one gigabyte. More 
than enough to hold the entire 
Encyclopedia Britannica! 



Optical disks have good transfer rates, about 
150Kbyr.es per second, while most hard disks are in the 
96Kbyte range. Data transfer can be speedy on an 
optical disk, once the location is found. Average track- 
to-track seek times run in the 1 ms range for the optical 
disk, while they average 3 ms for the standard 10- 
megabyte hard disk. The reason the optical disk is 
quicker is the mirrored head has a sequential access 
range of 40 nearby tracks without a move, while the 
fixed disk's head must move from track to track. Further, 
data on an optical disk remain sequential, while they 
become random on a hard disk that has been 
accessed a great deal. 

In favor of optical disks is storage. The average 
optical disk can store between 200 and 500 megabytes 
of data, while high-performance disks approach 1 
gigabyte. This contrasts markedly with the average hard 
disk that stores only 10 megabytes of data. 



SEPTEMBER 1986 — ComputerDigest 15 



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Unique address scheme 

An optical disk has a unique address scheme. Since 
it is based on digital audio recordins technology we 
must think in those terms. So, we must first consider 
the optical disk as "playing," rather than accessing or 
running. 

' Each disk plays (records) for 60 minutes and each 
minute is divided into 60 seconds. This is the basis of 
the optical disk addressing. There is one more factor, 
the sector number. 

Instead of addressing a piece of data as X track-Y 
sector as on a traditional hard or floppy disk, the 
optical disk addresses it as X-minutes-Y-seconds-Z- 
sectors. A third dimension has been added to this 
relationship. It means that current software and 
directory addressing systems have to be rewritten to 
work with the new address mode. 

This type of addressing is important given the 



changing nature of the data tracks and the number of 
sectors. In this manner, the three coordinates locate a 
given piece of data with pinpoint accuracy 

The read-write head consists of mirrors; a laser data 
decoder, and read circuitry It is more compiex than a 
typical read -write head on a hard or floppy disk. 

As the head records each block of data, a correction 
code is generated. That error correction code mirrors 
the information stored in a particular sector so if 
something is corrupted during the recording session, 
there is backup data encoded so the information will 
be read correctly when called for. This cuts the amount 
of space available for storage, but ensures that data will 
be read correctly. 

Despite their performance problems, optical disks 
represent great potential for the microcomputer user 
and industry Now you know why the optical disk is the 
hot ticket in town this year-^fflpv 



16 ComputerDigest — sr.PTFMBrR 1986 



• 400 MHz lo 900 MHz 

• 950 MHz to (450 MHz 

• Any 500-MHz band between 300 
and 1500 MHz 

• 3,700 MHz to 4,200 MHz. 
That combination of bands 

makes it possible for the installer 
to detect and display either a full 
500-MHz-wide satellite downlink, 
or, with the assistance of the unit's 
controls, any span as narrow as 2 
MHz within any of the covered 
bands. 

The 3,700- to 4,200-MHz band 
covers the satellite downlink fre- 
quencies. A built-in low-noise am- 
plifier can be coupled to the TVRO 
antenna of the system to be in- 
stalled or to a separate horn anten- 
na. In either case, the analyzer can 
be used to display both the desir- 
ed signal and any interfering sig- 
nals directly. 

The other five bands cover all of 
the commonly found TVRO IF's 
(intermediate Frequencies). That 
allows the system installer to verify 
the performance of downcon- 
verter and LNB (Low-Noise Block 
Downconverter) units, to check 
cable losses and fittings, to mea- 
sure distribution system param- 
eters, and even to check for the 
correct operation of a cable-TV 
system. 

What made it possible 

Low-cost microwave test equip- 
ment has been feasible for several 
years. However, the specialized 
knowledge that designers of TVRO 
receivers had acquired was miss- 
ing. In particular, flat mixers and 
flat sweep oscillators had to be de- 
veloped using the same low-cost 
approach as TVRO receivers. 
Some exciting developments in 
YIG ( Ktrium- Iron-Car net) os- 
cillator designs also helped pave 
the way for low-cost spectrum ana- 
lyzers and other high-frequency 
test equipment. 

For example, other generally- 
available test gear can provide: di- 
rect frequency readout of carriers 
to 4,200 MHz (accurate to 1 MHz) 
for under $1,000; accurate readout 
at 4,200 MHz of signal levels to 
within ±2 dB for under 5500; and 
direction-finding interference-lo- 
cating systems accurate to within 5 
degrees for under $600. You can 
even purchase microwave signal 
generators capable of generating 



significant amounts of power 
modulated by color bars and an 
audio tone, or by your own video 
source (such as a tape deck or a 
video camera), for under $1,000. 
None of that equipment was prac- 
tical, and a great deal of it was sim- 
ply impossible, as little as two 
years ago. 

The new microwave gear can be 
put to use in other bands as well. 
For example, Ku-band equipment 
(which operates in the 11- and 12- 
CHz bands) may be tested and 
aligned by simply connecting an 
LNB ahead of a 4,200-MHz instru- 



ment. That's a cost-effective solu- 
tion to a potentially sticky prob- 
lem, because an LNB can be 
obtained for under $200. 

Other fields may also benefit 
from advances made in microwave 
test instrumentation. Virtually any 
electrical quantity can now be 
measured with a high degree of 
accuracy at frequencies as high as 
4,200 MHz, and even higher. 

So if you service or install high- 
frequency equipment of any sort, 
you should be grateful to the 
TVRO industry — advances made 
there will henefit all of us. R-E 



SCRAMBLE-FAX 

SCRAMBLE-FAX 

from Bob Cooper 

IF satellite scrambling is important to you, here is a single 
source of timely, confidential information of great value; 
SCR AMBLE- FAX. Bob Cooper is routinely gathering all of the 
important scrambling information (who, what, when, where and how) 
and compiling it in printed form in an important newsletter called 
SCRAM BLE-FAX tm . Sources for pirate decoders, reports on attempts 
to 'beat the system', full lists of who is scrambling, how and when. 
Each issue of SCRAM BLE-FAX is timely and new; but, each issue 
is a detailed encyclopedia of scrambling information and totally 
complete. 

REPORTS on M/A-Com efforts to shut down 
pirate units, exporting of bootleg descramblers 
outside of the USA, complete listings of all (37+) 
channels now scrambling and those planning to 
scramble. The activities of DESug, the DES Users 
Group, and their progress on 'breaking' the 
Videocipher 'code', modifying receivers to accept 
Videccipher and much-much more. 




WESTAR Cofnmunlealions/Westcom, the Toronto area alleged 
manufacturer of 'pirate decoders' tor HBO/Showtime and other 
Videocipher type scrambled services reportedly has been sow to a hew 
group cl investors; all Ca radian. Toe firm has been often ng their pirate- 
type decoder unit for J50Q {US) tor several weeks claiming il decodes 
all Videocipher scrambled video plus audio signals. Attempts to locate 
the lirm other then through their BOO telephone number (1-800/265' 
5675) typically meet with failure and the firm is quick to explain that 
it would be inappropriate for them to identify Iheir actual street address 
locslnn (SCRAM8U-FAX suggests you try 504 Iroquois Shore. Oakville, 
Ontario; and A 1 6/W2-287? as their non-SOO telco). 



EACH issue of SCRAMBLE-FAX is 
sent to you via A! R-mail the very day 
your order is entered. Simply call 
305/771-0505 to order your copy 
(have VISA or Mastercharge card 
handy) orwrite for yourcopy enclos- 
ing payment for $10 (US funds) to 
the address shown below. PLUS — 
each issue is 'supported' by a 
SCRAMBLE-FAX 'Hotline' tele- 
phone updating service, 

DIAL 305/771-0575 anytime for a complete update on the status 
of scrambling. 'Hotline' recorded reports are provided by Bob Cooper 
as an 'instant update' to SCRAMBLE-FAX and carry fast-breaking 
news items of interest to the scrambling scene. But have your 
notebook and pen handy; each 'Hotline' report contains many 
telephone numbers and addresses you will want to retain! 

SCRAM BLE-FAX b v BobCo °p^ 

305/771-0505 or for free 'Hotline' service, 305/771-0575. To order 
by mail, send check/money order or enclose VISA/ Mastercharge 
number and expiration date: CSD Magazine, P.O. Box 100858, Ft 
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73 



Robotics 



Position sensing 

you don't have to work with a 
robot arm for long to realize that 
position information is highly im- 
portant. There are numerous ways 
of obtaining that sort of informa- 
tion; let's examine several. 

Digital position sensing 

Most digital approaches to posi- 
tion sensing involve optical de- 
vices. Recently in this column we 
discussed tactile sensing using IR 
emitters and detectors. Some of 
the same approaches can be used 
for position sensing. 

For example, a device called an 
optical shaft encoder or an optical 
interrupter encodes the position 
of a shaft by means of opto-elec- 
tronics. An infrared (IR) detector/ 
emitter pair couples to the shaft of 
a motor or the pivot of a robot arm 
and provides a series of digital 
pulses. The encoder requires only 
a source of five-voft power. How 
does it work? 

A disk like the one shown in Fig. 
1 is used to interrupt a beam of 
infrared light passing from an LED 




FIG.1 

g to a photo-transistor. Overall the 

z disk is transparent, but it has dark 

§ stripes that block the IR 

o periodically as it spins. The LED 

!j and the transistor are integrated in 

5 a single package, as shown in Fig. 

5 2. The encoder disk is attached to 

£ the end of a rotating shaft, and 



then it passes through the slot in 
the optical interrupter. As the shaft 
turns, the disk rotates, so the dark 
areas of the disk periodically pre- 
vent the LED light from reaching 
the photo-transistor. The output of 
the detector is a series of pulses 
that may be squared up and fed to 
digital control circuitry. 

The disk is manufactured so that 
the distance between each radial 
stripe is equal. So the number of 
pulses that are output indicate 
how far the shaft has turned. In- 
dustrial optical encoders may have 
several hundred, or a thousand or 
more divisions. 




FIG. 2 

Commerical encoder disks are 
usually expensive because they 
are manufactured under tight me- 
chanical tolerances. In addition, 
they offer a minimum of 256 slits. 
For purposes of experimentation, 
sixteen slits are sufficient because 
hobbyist-grade motors cannot be 
positioned very accurately. 

You could photocopy the disk in 
Fig. 1 on a piece of acrylic to 
provide position information for a 
Milton Bradley Robotix arm. The 
basic idea is sbown in Fig. 3. 




MARK J. ROBILLARD, 

ROBOTICS EDITOR 




STRUCTURE 
MEMBER 



nxr 



OPTICAL 
INTERHUPTER 




X rAi 




o 



MOTOR 



FIG. 3 



The optical interrupter is readily 
available, but if you have trouble 
locating one, or if you would like 
to purchase some encoder disks, 
MJR Digital (Mason Road, Milford, 
NH 03055) has an experimental kit 
consisting of nine transmissive en- 
coder disks, nine reflective en- 
coder disks, five H22A1 optical in- 
terrupters, and an application note 
available for $19.95. We'll discuss 
use of the reflective encoder disks 
below. 

Because two connections go to 
ground, only three wires must be 
brought to the encoder. In addi- 
tion, several encoders may share 
the ground and five volt lines. 

To use the encoder, the comput- 
er that controls the motor must 
monitor the output of the en- 
coder. To begin a motion se- 
quence, the arm must be 
"homed." In other words, the 
joint (or joints) in question must 
be brought to a limit — all the way 
up, down, left, right, etc. 

The computer must then read 
the status of the encoder. If the 



74 



output is low, then any subse- 
quent high indicates movement. 
Conversely, if the initial reading is 
low, then subsequent highs indi- 
cate an absence of movement. It's 
important to know whether you're 
starting with a high or a low; other- 
wise you may not be able to return 
the arm to the home position 
accurately. 

To move the arm to a specified 
position, load a counter with the 
number of slits that must be count- 
ed. Then, after homing the arm, 
turn on its motor and monitor the 
encoder's output for a pulse. 
When a high or a low (as pre- 
viously described) is detected, 
decrement the internal counter. 
Repeat that operation until the 
counter has a value of zero. At that 
point the arm should be in the de- 
sired position. 

You could perform the counting 
in hardware (without a computer) 
if you like. Doing that is simply a 
matter of using a counter IC and a 
logic gate to shut the motor off 
when the counter reaches zero. 

Reflectance decoder 

In some situations, a 
reflectance-type encoder disk is 
more practical. Rather than a clear 
disk with dark stripes, a reflec- 
tance disk is basically reflective 
with dark stripes. It is used as 
shown in Fig. 4. 



REFLECTANCE-TYPE 
ENCODER- 
WHEEL 



transmissive disk. That data can be 
used to position the arm as pre- 
viously described. 

Analog sensing 

Of course, there are other ways 
to sense the position of an arm. An 
analog approach might use a varia- 
ble resistor, an A/D converter, and 
a little software. The shaft of a po- 
tentiometer is connected to the 
pivot point of a robot's arm, so the 
potentiometer's resistance should 
provide an accurate indication of 



the arm's position. The voltage 
across that resistor would be read 
by the A/D converter, and the con- 
trol computer could then use that 
information to make an intelligent 
decision about what step should 
be done next. 

The arm must start from a known 
position, so, on power up, the arm 
should be homed. That is best ac- 
complished by rotating each pivot 
until a microswitch (used as a limit 
indicator) is activated. At that point 
motion must halt. Then the control 




A beam of infrared light is emit- 
ted from an IR emitter at an angle. 
An IR detector is mounted at a 
complementary angle. Light will 
be reflected from the reflective 
areas of the disk, and not from the 
striped areas. As the joint moves, 
the wheel turns, so the output of 
the detector is a series a highs and 
lows, like those produced by the 



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computer should check the out- 
put of the A/D device. The voltage 
read there represents a reference 
point in relation to which other 
positions are known. 

Some A/D converters require 
supply voltages of ±12 or even 
±15 volts. However, there are sev- 
eral 5-voit A/D IC's on the market. 
For example, National Semicon- 
ductor's A/D0816 can digitize 16 
channels of analog information. 
Each channel has eight bits, so any 
input between and 5 volts will be 
converted to one of 256 digital val- 
ues in steps of about 20 mV. Other 
A/D IC's provide 12 bits, for a total 
of 40% discrete values. 

There are several drawbacks to 
the analog approach. The first is 
that the potentiometer must be 
coupled physically to the arm's 
pivot, and that may be difficult. 
Also, the mechanical drag of the 
potentiometer may adversely af- 
fect the operation of the arm. And 
for the beginner, the most serious 
drawback may be creating the soft- 
ware required to operate the A/D 
converter. 

Speed may also be a problem. 
Many A/D converters operate 
much slower than the digital sys- 
tems controlling them. Often a 
computer must wait until the A/D 
converter is ready. 

A typical computer-to-A/D di- 
alog might go like this: The com- 
puter asks for the current reading, 
then the A/D works on the re- 
quest. Some hundreds of microse- 
conds later, the A/D signals the 
computer that the current reading 
is ready. Then the computer reads 
the value. If necessary, the process 
then repeats. 

The speed problem can be al- 
leviated by using a faster A/D con- 
verter. However, they're harder to 
find and more expensive than run- 
of-the-mill hobbyist-grade de- 
vices. And for experimental pur- 
poses, a slow A/D converter 
should prove to be quite suffi- 
ce cient. 

As you can see, there are a 



o 



o number of ways of gaining posi- 



h tion information about a robot 

"J arm. Some of those methods are 

4? more useful than others in dif- 

5 ferent circumstances, but the digi- 

< tal approach is generally the 
simplest to implement as well as 

76 the most accurate. R-E 



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PROJECTS FOR 

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77 



Service 
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78 



Customer psychology 

EVERYBODY HAS HAD THIS EXPERIENCE: 

you're ready to fix a set, and sud- 
denly you go blank! You look at 
the chassis, and it resembles a 
cake-pan full of firecrackers! 
When you go blank like that, 
there's only one thing to do: Get 
away from it for a while. Go drink a 
cup of coffee, or do something to- 
tally different for awhile. I know 
that method works; I've done it a 
million times myself. 

The LGC's 

While you're away, what Her- 
cule Poirot calls the tittle Grey 
Cells in your brain will continue 
working. The LGC's keep working 
even though your conscious mind 
thinks that it's completely off the 
problem. If you're lucky, they'll 
come up with the right answer, or 
at least a more logical one. So, 
when you return, you can usually 
sit down and fix your set right 
away. 

The subconscious mind is avery 
handy test instrument. Leave it 
alone and it will come up with the 
answer. The only things it can't fix 
are imaginary problems. And 
they're more real than you might 
think. 

For example, a cranky old man 
had a TV set that seemed (to me) to 
be working perfectly. I was kneel- 
ing behind the set when suddenly 
he said, "There! There! What 
makes it do that?" 1 couldn't see 
that anything at all had happened. 

So I tried a bit of psychology on 
him. I turned the ACC control up 
to the point where the picture be- 
came completely white. Then 1 
said, "I can't tell how it looks from 
back here. You tell me when I get it 
right." I brought the ACC control 



down a littie at a time, and finally 
he said, "There, there! That's just 
right!" So my service call was 
really an exercise in Applied Cus- 
tomer Psychology — but it worked. 
The customer was satisfied, so 1 
closed my tube caddy and went 
home. 




FIG. 1 

Another thing to watch out for is 
a situation like like that pictured in 
Fig. 1, Try to establish a rela- 
tionship with one customer — oth- 
erwise your LGC's may require 
servicing of their own! 

It may be hard to satisfy a cus- 
tomer who insists on watching a 
distant, fading station. You'll just 
have to shoot from the hip. Try de- 
liberately rotating the antenna 
(from outside, if necessary) away 
from the desired station. Next 
gradually bring it back on target. 
Then ask your customer, "How's 
that?" and chances are good that 
he'll say. "There. That's much bet- 
ter." When you hear that, you're in 
like flint. 

That kind of trick only works 
with older sets, which have the 
contrast and AGC controls 




^ ■' 



JACK DARR, 

SERVICE EDITOR 

mounted on the rear. If they're 
front-mounted, you'll have to fig- 
ure out some other trick. And, 
wherever they're located, you'll 
just have to use whatever controls 
are present — and sometimes there 
aren't enough of them! Do the 
best you can with what you have to 
work with! 

Of course, before you try psy- 
chology, make sure that the set 
really is working properly — after 
all, some TV's have real troubles. If 
you can't find anything else, clean 
all of the customer-operated con- 
trols (contrast, volume, etc.) so 
that they don't upset the picture 
when they're adjusted. 

Fortunately, "picky" customers 
make up a very small percentage 
of the total population. But, when 
you run into one, you have to have 
a way to deal with him (or her). It's 
not easy, but it can be done. It may 
take a little extra time, but it's time 
well spent if the customer is pleas- 
ed. And if he is pleased with you — 
and your work — he'll tell all the 
neighbors about you, and that's 
good for business. R-E 



SERVICE 



QUESTIONS 

NO HORIZONTAL SWEEP 
/ have no horizontal sweep on an 
RCA CTC-71, just a straight vertical 
line. I changed the flyback; no im- 
provement. Then I disconnected the 
tripier, the yoke, and the con- 
vergence panel; still no change. DC 
supply voltages are about normal. 
I'm completely confused. Help! — R. 
B., Toledo, OH. 
Say no more; help is on the way. 



Look at your DC voltage readings, 
especially on the emitter of the 
horizontal output transistor. You 
should see +5.5 volts; since you 
read 0.0, the transistor is either 
open, or the bias is way off. Re- 
move the transistor from the cir- 
cuit and measure the DC resis- 
tance of all junctions, especially 
the collector-emitter junction. 
Chances are that it is open. 

MISCONVERGENCE IN SONY 
I've got a Sony that's got me com- 
pletely baffled. It has a good picture 
but the screens will not align! The 
red screen is a full inch to the left. 
Horizontal static has no effect. I've 
changed the convergence trans- 
former; no luck. Is it the picture 
tube?—W.K., Lansing, ML 

Well, you've got a dandy, and 
I'm sorry you asked! However, 
something is causing it. Just for 
luck, give it a good going-G'^er 
with a degaussing coil, especially 
around the neck and the nearby 
parts. 

Strictly from way out in left field, 
it could have been caused by a 
lightning strike near the set. I have 
seen sets that were affected by 
lightning strikes; for example, 
convergence on an American set 
with a triad gun was severely dis- 
rupted. Degaussing cured that 
one, and I hope it will help you. 
Good luck! 

SCANNER BOOSTER 
Is it possible to amplify the signal 
before it is fed to a scanner? f live in 
an area where I need to increase the 
signal to get more audio. Can you tell 
me which type of antenna is best for 
signal gain?— T. W., Rogers, AR. 

Yes, you can use a booster like 
the ones used for TV. just be sure 
to get one that covers your fre- 
quency band. The Capri unit you 
mentioned should probably work. 

The highest-gain antenna is a 
Yagi. If you're not working very 
low frequencies, you might try 
one. 

A Yagi has a dipole, a reflector 
behind it, and from one to three 
directors in front of it. You can find 
drawings and dimensions in any 
good antenna handbook. Other- 
wise, a dipoie antenna with a re- 
flector located Va wavelength be- 
hind it is pretty sensitive. Aim it at a 
right angle to the desired signal. 



LOW VOLTAGE IN SANYO 
I've got a Sanyo 91C63. Several re- 
sistors were low in value so I 
replaced them. Now the power-sup- 
ply voltage is lower than normal. I 
can't find any sign of a short, so I 
don't understand what's going on. — 
K. P., Zumbrota MN. 

This sounds like a problem 
we've had many times! Check the 
input filter capacitor. If it's open, 
or low in value, your B+ will be 
low with no sign of a short circuit. 
The capacitor doesn't have the ca- 
pacitance to maintain voltage un- 
der normal load. 

You can check that capacitor 
easily: Just bridge another one 
about the same size across it and 
see if the voltage comes back up. 

FOREIGN RADIO 
/ have acquired a radio that was 
made in Poland. It looks very much 
like a Grundig. I need service infor- 
mation and parts for it, especially a 
missing loopstick antenna. Can you 
help?—D. P., Ft. Dodge, I A. 

Probably not much, but I'll try. It 
could be a Grundig; look up the 
tube lineup and see if you can 
match it with a Grundig that you 
have a schematic for. Since all 
small radios are basically the 
same, that should give you 
enough information. 

As for the loopstick, does the 
radio have a dial so that you can 
tell which bands it can receive? If it 
can receive the standard U.S. 
broadcast band, any loopstick 
should work. If not, try your signal 
generator. See which bands are 
covered by whistling them in. It 
should be fun (???) to get it going. 

ZENITH COLOR COIL 
/ have a Zenith 20Y1C50. When 
making the color adjustments, the 
phase-shift coil fell apart. I can't find 
a replacement for it anywhere. 
Zenith and Sams both list replace- 
ments which are themselves no lon- 
ger available!— S. B., Bronx, NY. 

I see the coil (transformer, actu- 
ally) you mean. It couples the 
color signal into the two color am- 
plifiers. I haven't been able to lo- 
cate a direct sub for that part, but it 
appears that a J. W. Miller part no. 
6092 or CO-1099 might work. 
They're color circuit coils, and 
both have dual secondaries like 
yours. R-E 



Capacitance, 

logic and more. 

For less. 

Now, a fully-loaded DMM combines 
a capacitance meter, logic probe, and 
an hFE meter, all for the price of a DMM. 

TTL Logic Probe: 20 MHz 
Hi/lo/off indications 
Detects 25nS pulse width 
Capacitance: 5 ranges (2nF to 2G>xF) 
hFE(NPNorPNP):l range (1000) 
DMM: DCV-5 ranges (.2V to lkV) 
ACV-5 ranges (,2V to 750V) 
DCA-4 ranges (200/iA to 10A) 
ACA-3 ranges (20mA to 10A) 
Ohms -7 ranges (200 Ohms 

to 2000 Megohms) 
Continuity beeper 
Diode check 
Built-in bail 
Anti-skid pads 

See one now at your local Beckman 
Industrial distributor. 

DM25L...S89 95 * 




•SmgestadliiT prat f JUS) wrMwItr-ry, tot lads aflfl - 

Beckman Industrial Corporation 

A Subsidiary of Emerson Electric Company 

630 Puente Street, Brea, CA 9262] 

(714)671-4800 

C Copyright 1985 Urtknun Industrial Corporation 



CIRCLE 98 ON FREE INFORMATION CARD 



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83 



Communications 
Corner 




Communications wars 



A FIERCE BEHIND-THE-SCENES WAR HAS 

raged for almost the entire 40-year 
history of radio communications. 
The war has been fought between 
the manufacturers of transmitting 
and those of receiving equipment. 
Sometimes it surfaces as an appeal 
to the FCC for some kind of regula- 
tion providing relief. At other 
times it has resulted in legal action 
between formerly friendly neigh- 
bors, or even in a western-type 
shoot-out. 

The source of the dispute is 
RFI — Radio frequency /inter- 
ference. RFI is usually considered 
to be interference that is gener- 
ated by something external to re- 
ceiving equipment: for example, 
the hash that is sometimes induc- 
ed in telephones by nearby per- 
sonal computers. 

Often, however, we use the 
term RFI to refer to interference 
generated within a receiver by an 
otherwise legal external source, 
even though that type of inter- 
ference is not necessarily RFI in 
the true sense of the word. It is 
that pseudo-RFl which is really the 
problem in much consumer 
equipment, including tape record- 
ers, telephones, TV's, VCR's, etc. 
Pseudo-RFl can manifest itself in 
various forms including inter- 
ference or image reversal in TV's, 
transmitter modulation in sound 
equipment and telephones, or 
cross-modulation products in re- 
g ceivers (wherein the listener hears 
z stations to which the receiver is 
§ not tuned). Interference created 
o by pseudo-RFl takes other forms, 
j but those are usually considered 
£J the biggies. 

5 Often, the cause of pseudo-RFl 
t£ (and therefore the war for which it 



84 



is responsible) is not a radio or TV 
transmitter — which usually deliv- 
ers a clean signal — but cost-cut- 
ting in the receiver. 

No filters 

For many years, in order to trim 
a few dollars off the retail price of a 
piece of consumer equipment, 
much of the entertainment-equip- 
ment industry resisted installing 
filters. For example, until the ad- 
vent of color TV it was highly un- 
usual to find a "standard brand" 
TV that incorporated a lowpass fil- 
ter in the tuner input to attenuate 
communication signals below 50 
MHz. 

Without the filter, an amateur, 
CB, or low-band VHF transmitter, 
or even a diathermy machine, 
could easily overload nearby TV 
front-ends and produce picture re- 
versal or loss of synchronization. 
Although it is possible to keep the 
sub-50-MHz signals out of the TV 
by installing a highpass filter in the 
antenna lead-in (as shown in Fig. 
1), unless the filter is properly in- 
stalled — which is difficult when 
unshielded twinlead is used — ra- 
diation from strong local transmit- 
ters can be induced into the 
antenna lead-in after the highpass 
filter. 

The term "shock-field" refers to 
the extremely strong RF energy in 
the immediate locality of a trans- 
mitter. Sound equipment that is 
located in the shock-field is par- 
ticularly susceptible to RF, which 
can often bypass shielding. Prob- 
lems generated by that RF usually 
manifest themselves as transmitter 
modulation heard in the back- 
ground, or during quiet periods. 
Shock-field interference is even 



HERB FRIEDMAN, 

COMMUNICATIONS EDITOR 

known to have produced er- 
roneous traces on a hospital's EKC 
recorder. 




INTERFERING 
TRANSMITTER 



F1G.1 

In vacuum-tube amplifiers, 
whose high-impedance circuits 
are prone to RF interference, 
pseudo-RFl in audio amplifiers 
caused by local transmitters was 
filtered by brute force using filter 
chokes and capacitors in the wir- 
ing of the low-level preamplifiers. 

It was hoped that the low imped- 
ances common to solid-state de- 
vices would alleviate the problem 
because, as a general rule, the 
lower a circuit's impedance, the 
less susceptible that circuit is to 
pseudo-RFl. Unfortunately, things 
didn't work out as hoped. The ear- 
liest circuit designs — many of 
which are still used today — em- 
ploy transistors, and transistors 
consist of diode junctions. If there 
is enough RF energy in the circuit 
to cause the diode(s) to conduct, 
the stage becomes a rectifier, a 
broadband amplifier, or both. If 




R-2000 

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Superior engineering, quality, and 
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The R-2000 receiver has the most 
often- needed features for the serious or 
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Listen in on overseas news, music, 
and commentary. "Listen up" on the 
VHP public service and Amateur radio 
frequencies, as well as aircraft and busi- 
ness band communications with the 
R-2000 and VC-10 option. The R-2000 
has a muting circuit so you can monitor 
your Amateur radio station's signal 
quality. 

• Covers 150 kHz -30 MHz in 30 bands. 

• All mode: USB, LSB, CW, AM, FM. 

• Digital VFO's. 50-Hz, 500-Hz or 5-kHz 
steps. F. LOCK switch. 



• Ten memories store frequency, band, and 
mode data. Each memory may be tuned 
as a VFO, 

• Lithium batt. memory back-up. 

• Memory scan. 

• Programmable band scan. 

• Fluorescent tube digital display of 
frequency (100 Hz resolution) or time. 

• Dual 24-hour quartz clocks, with timer. 

• Three built-in IF filters with NARROW /WIDE 
selector switch. (CW filter optional.) 

• Squelch circuit, all mode, built-in. 

• Noise blanker built-in. 

• Large front mounted speaker. 

• RFstep attenuator. (0-10-20-30 dB.) 

• AGC switch, (Slow-Fast,) 

• "S" meter, with SINPO scale. 

• High and low impedance antenna 
terminals. 

• 100/120/220/240 VAC operation. 

• RECORD output jack, 

• Timer REMOTE output (not for AC power). 

• Muting terminals. 



Optional accessories: 



• VC-10 VHF converter for R-2000 covers 
118-174 MHz 

• YG-455C 500 Hz CW filter for R-2000 

• HS-4 Headphones 

• HS-5 Deluxe headphones 

• HS-6 Lightweight headphones 

• HS-7 Micro headphones 

• DCK-1 DC cable kit for 13.8 VDC operation 

Additional information on Kenwood all-band 
receivers is available from authorized dealers. 




Service manuals are available for all receivers and most accessortes 

Specifications and prices suoiect to change without notice or obligation 



KENWOOD 

TRIO-KENWOOD COMMUNICATIONS 
1111 West Walnut Street 
Compton. California 90220 

CIRCLE 102 ON FREE INFORMATION CARD 



COMMUNICATIONS CORNER 



continued from page 84 



the interference is caused by an 
AM transmitter, the RF1 is detected 
just as it would be in an old-fash- 
ioned crystal radio, and the inter- 
ference will be crystal clear (pun 
intended). 

If the stage is a high-gain pre- 
amplifier, such as a magnetic pho- 
no preamp, and the interference is 
caused by a local low-band VHF 
(FM) transmitter, the listener hears 
the VHF transmitter's FM modula- 




tion in the background because, 
since the diode junction is non- 




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86 



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linear, it functions as a slope de- 
tector that will produce audio out- 
put from an FM signal. 

If the stage is an RF amplifier, the 
diode causes it to function as a 
mixer that will output sum and dif- 
ference signals, as well as the orig- 
inal input signal. Between the sum 
and difference frequencies many 
other frequencies may appear as 
by-products of the heterodyne 
(mixing) process. The result is that 
the listener may be subject to a 
garble of signals, or intermittent 
bursts of interference from strong 
local transmitters of any kind. 

Much arm-twisting by industry 
groups and the FCC has convinced 
many manufacturers of consumer 
equipment to include various 
kinds of filters to prevent pseudo- 
RFI from lessening or destroying 
signal quality. However, stu- 
pidity — or just plain stubborn- 
ness — still reigns supreme among 
some circuit designers. For exam- 
ple, it is easy to design audio pre- 
amplifiers using FET's because it's 
usually easier to bridge the output 
of one stage with a circuit that has 
a high-impedance input than it is 
to match the impedance of that 
stage. In fact, any reasonably com- 
petent junior high school student 
could design a totally bridged am- 
plifier. 

Figure2 shows the simplified cir- 
cuit diagram of a preamplifier used 
in a recently-introduced consumer 
device. The input device is a FET, 
whose effective input impedance 
in this application is as high as a 
vacuum tube's input impedance. 
Although bridging with a FET is 
cheap and saves on circuit design 
time, it is precisely that kind of 
thinking which has produced the 
40-year war between the users of 
communications equipment and 
those who watch TV, listen to the 
radio, and to recordings. The 
point is that, in this age of low- 
impedance devices and circuits, 
we must question the wisdom of 
anyone using that type of design, 
because the circuit is extremely 
sensitive to RF-pickup. 

And it's ironic that the most diffi- 
cult part of the problem is explain- 
ing to someone why the inter- 
ference is caused not by your 
amateur, CB, or VHF rig, but that 
person's poorly-designed $3000 
entertainment center. R-E 



CIRCLE 196 ON FREE INFORMATION CARD 



LETTERS 



continued from page 22 



stating, albeit obliquely, that there 
could be something beyond the 
realm of known physics that influ- 
ences the Kirlian "aura." 

The generation of Kirlian im- 
ages, although a complex process 
subject to many variables that are 
not easily controlled, even in the 
laboratory {e. g., pressure, tem- 
perature, conductive residues de- 
posited by the object being 
tested — -or left over on the elec- 
trode from the previous object, ex- 
posure time, etc.), is explainable 
without invoking the paranormal. 

For readers who would care to 
learn more about the physical as- 
pects of Kirlian photography, an 
excellent study was published in 
the Spring issue of Skeptical In- 
quirer, a quarterly that is pub- 
lished by the Committee for the 
Scientific Investigation of the Para- 
normal (CSICOP). 

Also, several years ago, in the 
trade journal Functional Photogra- 
phy, an article presented a fairly 
convincing theory of how the 
Kirlian corona interacts with the 
dyes in color film to yield those 
complex images. 

I really enjoy Radio-Electronics 
magazine, particularly the con- 
struction projects. However, it's 
bad enough that Kirlian photogra- 
phy, pyramid power dowsing, and 
other such stuff get favorable 
coverage in the news media and 
supermarket tabloids. Let's at least 
try to keep it out of informed tech- 
nical publications. 
STEVE HANSEN, 
Amherst Ntf 

MODULAR ROBOTS 

I've been waiting for you to 
cover robots. It's took awhile, but 
you did it right in the March 1986 
Radio-Electronics. 

I'm an electronics technician (U. 
S. N.) by vocation, but I'm also an 
electronics hobbyist, because I 
want toys and tools that do more 
but cost less. I'd love to see you 
build on the March issue and do 
with robots what you've done with 
TV decoders, power supplies, and 
virtually everything else. I'd like to 
see plans and ideas for home- 
brew modular robots. 



All told, it could be a big project, 
and could keep a regular depart- 
ment full for years to come. I'm 
sure that I'm not the only reader 
who's willing to submit hints, help, 
and new ideas. My plans are to 
start with a microprocessor-con- 
trolled base (rover type) then add 
various modules such as body, 
brain, various sensors, manip- 
ulators, interfaces etc. 

Along those lines, there are 
many, many projects that I would 
like to see, and some are yet to be 



thought up! 

Right now, the robot industry is 
"backyard" at best. I'd like to see 
the hobbyists, not Daddy War- 
bucks, make the robot a house- 
hold tool. The computer industry 
will easily fall into place with soft- 
ware and interfaces. The robot will 
develop faster and farther if home- 
builts have more in common than 
so-called standard RS-232 inter- 
faces, or dialects of BASIC. 
SCOTT ZINN 
Souda Bay Creek, NY R-E 





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CIRCLE 183 ON FREE INFORMATION CARD 






i 



Antique 

Radios 



Speakers and headphones 



THIS MONTH WE LL DISCUSS VARIOUS 

kinds of audio output devices in- 
cluding headphones, electro-dy- 
namic, magnetic, and permanent 
magnet speakers, and trou- 
bleshooting information about 
each type of reproducer. But be- 
fore we get to all of thai, let's take a 
look at the antique of the month. 

Looks good, doesn't work 

Early Zenith console radios like 
the1940-ish mode) shown in Fig. 1 
were very popular in their day, and 
many of them still are. That Zenith 
could receive several different 
bands, and it has a tuning eye and 
assorted tone controls. That par- 
ticular radio was chosen to make a 
point. Although it's in good out- 
ward condition, it will never play 
again. It is beyond repair because 
it has no tubes, no speaker, and a 
burned out transformer. But even 
though it's useless — as a radio — to 
a collector, it still has value as a 
display piece. For example, it 
could be used as a prop in a play or 
TV show. 

The Zenith will be donated to 
the Golden Radio Buffs of Mary- 
land, Inc. That organization 
doesn't collect radios and equip- 
ment; their interest is in broad- 
casting and personalities. They 
have a display at the Museum of 
Industry in Baltimore, MD. A few 
antique radios are on display there 
to set the mood while recordings 
of early radio programs are played. 
If you are interested in joining the 
Golden Radio Buffs, send an SASE 
to Gene Leitner at 7506 Iroquois 
Ave., Baltimore, MD 21219. 




5 Speaker history 



88 



Reproducers, like all chassis 



FIG. 1 

components, have seen many re- 
finements over the years, although 
the major innovations were mostly 
completed during the 1920's. As 
with most advances in radio, it's 
difficult to say who invented the 
loudspeaker. And, as in other 
areas of electronics, the names of 
many early experimenters are un- 
doubtedly lost. 

There are three basic types of 
speakers: magnetic (not to be 
confused with either of the follow- 
ing types), dynamic (also called 
electro-dynamic), and PM (Perma- 
nent Magnet). The names of the 
various types of speakers can be 
confusing. The names of magnetic 
speakers, for example, have many 
variations including the dynamic 
magnetic, diaphragm and horn, 
cone and armature, etc. Although 
all speakers operate magnetically, 
remember that the "magnetic" 




RICHARD D. FITCH, 

CONTRIBUTING EDITOR 

type of speaker differs from the 
other types in several significant 
ways. We'll discuss those dif- 
ferences below. 

The earliest reproducers were 
headphones, but by the mid 
1920's, magnetic horn-type speak- 
ers had supplanted earphones. 
Then came cone-type speakers, 
both single and double. And by 
1930 the electro-dynamic loud- 
speaker was the most popular au- 
dio output device. Later, the 
development of new alloys 
brought about the permanent 
magnet, which simplified radio 
circuitry, because PM speakers 
don't require a field coil (which is 
discussed below). 

Early radios were often sold 
without tubes, chassis, or speak- 
er; in fact, the schematics of many 
early radios seldom indicate any- 
thing after the audio output tube. 
The manufacturers left it to the 
consumer to decide which type of 
reproducer to use, and great de- 
bates raged regarding the merits 
of various types of speakers. And, 
because radios often came with- 
out speakers, the manufacture of 
speakers and cabinets, as well as 
headphones, constituted a thriv- 
ing business of its own. An exam- 
ple of each of the four major types 
of reproducer is shown in Fig. 2. 
Clockwise from the lower left are 
headphones, a magnetic speaker, 
a dynamic speaker, and a PM 
speaker. 

Early headphones were made by 
about half a dozen manufacturers, 
and all were basically the same. 
The headset shown in Fig. 2 is from 
about 1920 and was probably de- 
signed to be used by a telephone 
operator. It was made by C. 



Brandes, Inc., of New York; thai 
company later made speakers and 
radios too. The Brandes headset is 
more collectable than many an- 
tique radios. 




FIG. 2 

That magnetic headset operates 
by means of a diaphragm that is 
suspended above a magnet. Coils 
wound around the magnet cause 
the diaphragm to vibrate when 
current flows through those coils. 

Headphones have survived to 
the present day, but after speakers 
became generally available, they 
proved to be much more popular 
than headphones. Why did speak- 



ers become so popular? One rea- 
son is that the earphone cord 
severely restricts your freedom of 
movement. And only one person 
can listen at a time, although two 
friendly listeners can share a set of 
earphones if they put their heads 
together. 

So designers began thinking of 
better ways for peopie to enjoy ra- 
dio broadcasts. One method was 
simply to lay the headphones on a 
table and strap a megaphone to an 
earpiece. That method worked 
and was probably the beginning of 
the loudspeaker. But of course it 
left much to be desired, so design- 
ers continued their search for a 
more perfect reproducer. 

Speakers 

One early attempt at better 
sound reproduction is the mag- 
netic speaker. There are many vari- 
eties of magnetic speaker, but, in 
general, a magnetic speaker uses 
an armature to move a diaphragm, 
although some use an earphone 
coil and a cone or a horn attached 
to the diaphragm. 




FIG. 3 

Magnetic speakers, especially 
the various horn types, were pop- 
ular during the mid 1920's. One 
very popular magnetic speaker 
was RCA's model 100-A, which is 
shown in Fig. 3. There are still 
thousands of those speakers 
around, and many collectors have 
one or more. 

The electro-dynamic speaker 
became popular in the late 1920's 
and early 1930's. It requires a DC 
voltage to operate a field coil, 
which, as its name suggests, gen- 
erates the magnetic field that, in 
conjunction with the voice coil, 
causes the cone of the speaker to 
move. That field, of course, is gen- 




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CIRCLE 202 ON FREE INFORMATION CARD 



erated in later speakers by a per- 
manent magnet. The dynamic 
speakeralsotndudesa hum-buck- 
ing coil that cancels hum intro- 
duced by the field coil. 

Pros and cons 

There was much discussion of 
the relative merits of various types 
of speakers in the Iate1920's when 
the popularity of the dynamic type 
was increasing. Proponents of dy- 
namic speakers focused on the 
faults of the magnetic units, which 
are really just glorified earphones 
that produce weak, scratchy 
sound. They are, however, excel- 
lent collectables today. The main 
advantages of the magnetic units 
are their lower initial cost and their 
lack of hum. 

But, by the late 1920's, most lis- 
teners used dynamic speakers and 
never noticed the hum. Andaftera 
listener heard a dynamic speaker, 
it was difficult to return to a mag- 
netic speaker. 

However, economics some- 
times caused a listener to buy a 
magnetic rather than a dynamic 
speaker, because the latter often 
required a separate power pack 
(with rectifier) to drive the field 
coil. Of course, a well-informed 
consumer knew that there was no 
need to purchase a separate 
power pack if his radio's chassis 
had provisions for a field coil built 
in. 

Proponents of magnetic speak- 
ers pointed out that it was an ad- 
vantage not to have to drive a field 
or hum-bucking coil. No storage 
battery, rectifier, or filter was 
needed. And since no hum was 
introduced, there was no need for 
a hum-bucking coil. 

On the other hand, a magnetic 
speaker had problems reproduc- 
ing low notes. Even with a large 
horn or cone, it couldn't match 
the frequency response of a dy- 
namic speaker. Most people 
agreed (hat magnetic speakers suf- 
ficed for telephone use (which is 
where they began), but not for mu- 
sical reproduction. The slight hum 
produced by a dynamic speaker 
was preferable to lack of fidelity. 

Receiver manufacturers who 
didn't supply a reproducer with a 
receiver usually recommended 
that the consumer buy the more 
expensive unit, because that made 



the receiver itself seem better, so 
the consumer would be more like- 
ly to recommend that brand to 
other people. 

Radios made by Zenith, Radiola, 
Bremer Tully, and others could use 
various types of speakers. Magnet- 
ic speakers were more popular 
with early battery-operated sets 
such as those made by Dayton and 
Radiota. Some radios had both a 
jack for a magnetic speaker and 
terminals for a dynamic speaker. 

Troubleshooting headphones 

There is little that can go wrong 
with magnetic headphones elec- 
trically. So first check a troubled 
set mechanically. Remove the caps 
on the earpieces. The diaphragm 
should fall out — and maybe a few 
other things besides. Remove any 
dust, dirt, or other foreign objects, 
because they can prevent the di- 
aphragm from vibrating. 

The coil connections should be 
clearly visible, so make a con- 
tinuity test between the terminals 
and the plug. The coils may be 
open, but that's unlikely. The 
splice leading to the other ear- 
piece is a likely suspect if one side 
of the headset is dead. When you 
re-assemble the earpieces, pay at- 
tention to the diaphragm. Some 
have a painted side which should 
face out. 

Troubleshooting PM speakers 

Unlike the complicated speaker 
array of early radios, small PM 
speakers can be checked quickly, 
and they have few components 
that can go bad. The voice coil 
(also called the moving coil) and 
the audio output transformer are 
the primary sources of trouble. 
Others include an off-center voice 
coil, a warped cone, and a bent 
frame, all of which will distort the 
sound. The labor involved in try- 
ing to straighten a cone or frame, 
or center a voice coil, simply isn't 
worth the effort. Just replace the 
entire speaker. But if the results of 
a continuity test are negative, 
don't assume that the voice coil is 
bad. The trouble is most likely at a 
terminal, plug, or other soldered 
connection. The voice coil rarely 
develops an open in the winding. 

If you're not sure whether the 
speaker or some other compo- 
nent is at fault, the easiest way to 



check a small PM speaker is by 
substitution. Just make sure that 
you connect the speaker to the 
secondary of the output trans- 
former. Some transformers are 
mounted on the chassis, and 
others are mounted directly on the 
speaker frame. 

You may be able to salvage a 
seemingly open output trans- 
former. If a winding fails a con- 
tinuity test, the problem may be a 
solder joint. Just peei back some 
of the insulating paper to where 
the winding wire joins the hookup 
lead. If you don't find a bad joint 
there, it's usually cheaper to re- 
place the transformer than to re- 
pair it. 

Troubleshooting magnetic 
speakers 

Many repairs required by mag- 
netic speakers are mechanical. If 
the driving rod is loose, it may only 
require tightening the nut. If the 
center of the cone is torn, remove 
the rod and re-glue the cone. Re- 
pairing that type of cone is much 
easier than trying to attach a torn 
cone to the voice coil of a dynamic 
speaker. 

Since a magnetic speaker is built 
like an earphone, it can be check- 
ed like an earphone. Continuity 
can be measured between the coil 
terminals and the plug. Remove 
any dirt or dust that may interfere 
with operation of the diaphragm. 
The pin connected to the di- 
aphragm and to the center of the 
cone often breaks loose. A little 
glue around the area should fix it. 

An armature-activated magnetic 
speaker might have a problem 
with the armature's striking the 
pole pieces. That generates an 
easily-identifiable sound that oc- 
curs mostly on low notes. Those 
pole pieces, by the way, are partly 
what limited the popularity of that 
type of loudspeaker. Many people 
found the mechanical adjust- 
ments more trouble than they 
were worth. 

Troubleshooting dynamic 
speakers 

A dynamic speaker may suffer 
from any problem that a PM speak- 
er may suffer from, in addition to 
several of its own. Unwanted 
vibrations could be caused by a 
torn cone, dirt or metal particles, 



loose mounting screws, or other 
metal components on the loud- 
speaker's frame. Unlike PM speak- 
ers, most dynamic units provide a 
means of centering the voice coil. 

That is done with a device called 
a spider, which comes in several 
variations. Besides centering the 
voice coil, the stiff material the spi- 
der is made of helps the voice coil 
return to its neutral position when 
no signal is applied. When center- 
ing the voice coil with a spider, 
sometimes it helps to place some 
stiff paper around the coil. Doing 
that helps ensure that the coil 
won't rub after the spider is ad- 
justed. 

Unfortunately, you'll probably 
have to make every effort to repair 
a damaged speaker cone yourself. 
The old speaker reconer is a dying 
breed. 

Hum problems are easy to diag- 
nose. A hum bucking coil is wired 
in series with the secondary of the 
output transformer and the voice 
coil. When disconnecting the 
voice coil or output transformer 
leads, be careful not to reverse 
them in relation to each other. You 
continued on page 93 



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co 
m 

3 

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91 



Drawing 
Board 



Program corrections and lab set-up 





LISTING 


I— CORRECTED PROGRAM 


Address 


Op Code 


Source Code 


Comments 


0000 


AF 


XORA 


Zero the Accumulator 


0001 


26 OF 


LD H,0F 


Set the display number 


0003 


2EA0 


LD L,0A 


Set the loop counter 


0005 


7C 


LDA.H 


Load the Accumulator 


0006 


D3 FF 


OUT (FF),A 


Send it to the latch 


0008 


C3 00 1 1 


JP 001 1 


Go to delay subroutine 


000B 


25 


DECH 


Decrement port count 


000C 


2D 


DECL 


Decrement loop counter 


000D 


C2 05 00 


JP NZ 0005 


Do again if not zero 


0010 


76 


HALT 


End of the program 


0011 


1 1 83 8B 


LD DE.5161 


Preset the delay loop 


0014 


IB 


DEC DE 


Decrement the counter 


0016 


B3 


ORE 


OR with the low byte 


0015 


7A 


LDA.D 


Transfer the high byte 


0017 


C2 14 00 


JPNZO014 


Jump back if not zero 


001 A 


C3 0B00 


JP0008 


Return if finished 



o 



o 

rx 



u 



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rr 
92 



IT HAPPENS TO EVERYONE. I GOOFED 

when putting together the dem- 
onstration program for the Z80 cir- 
cuit in the March 1986 issue. I'm 
glad that several of you caught the 
mistakes and let me know about 
them, but I'm also a bit disap- 
pointed that only three people lei 
me know about it. Just for the rec- 
ord, if anybody sees what even 
looks like an error on my part, I'd 
be grateful if you'd take the time to 
drop me a card and point it out to 
me. The only way we'll profit from 
our discussions is to make sure 
that all the information presented 
here is correct. 

The three people who found 
mistakes are Paul Fargen of 
Louisville, KY, L. Barker of Chi- 
cago, lL, and Steven Gray of Orlan- 
do, FL. Some of the points they 
made are real screw-ups on my 
part, one is a typo, and the last is a 
matter of opinion. We'll deal with 
the out-and-out mistakes first. 



Delay loop 

The worst error occurred in 
lines 11-14, a deiay loop that was 
supposed to let the LED display 
remain stable for about half a sec- 
ond before displaying the next val- 
ue. My first mistake was in cal- 
culating the number of T cycles 
needed to go through the loop. I 
said that 14 were needed but in 
actual fact the delay loop takes 16 T 
cycles. The DEC DE instruction in 
line 12 takes 6, and the JP NZ in- 
struction in line 13 takes 10 cycfes. 

But even with the loop counter 
loaded with the correct number 
(in line 11), there was still a major 
problem. After the program en- 
tered the delay loop it would loop 
there forever. The reason is that 
the DEC DE instruction has no 
effect on the zero flag, and the 
zero flag is what we test to find out 
whether we can exit the delay 
loop. The program would con- 
tinue decrementing the DE regis- 




ROBERT C ROSS BL ATT, 

CIRCUITS EDITOR 

ter until reset, power-down, etc. 
The result would be that all the 
LED's on the output port would 
light up and stay lit. 

There are several ways to correct 
the problem. Probably the sim- 
plest approach involves realizing 
that when the loop counter 
reaches zero, both the D and the E 
registers will be zero. So, as shown 
in lines 13-15 of Listing 1, all we 
have to do is or the the two regis- 
ters with each other and test for a 
result of zero. If so, the program 
will jump back to the main display 
routine. However, adding the ex- 
tra lines of code forces us to 
change the value we stored in DE 
to control the delay loop. 

The 16 T cycles we had in the 
original loop increase to 24 be- 
cause the LD A,D and the OR E 
each take four T cycles. A half-sec- 
ond delay means we want to wait 
500,000 microseconds. Dividing 
that by 24 gives us 20,833 decimal 
or 5161 hex. Line 11 of the program 
loads that value into the DE regis- 
ter pair. 

Of course, the Z80's instruction 
set is rich enough for you to find 
several other ways of fixing the 
original program to correct the 
mistake in the delay loop. Asa mat- 
ter of fact, figuring out other ways 
to solve the problem is a good ex- 
ercise in programming! 

Typo 

There was a typo in line 3 of the 
original listing. The code printed 
in the column was LD A,A0. Thai's 
where we set the number of times 
we want the program to loop 
through the hex display. As it is, 
the program would loop through 
the display procedure 160 times. 



What happened was that the two 
digits were reversed; the correct 
value should have been 0A. Then 
the program would loop ten times, 
as I called for in the text. 

No RAM 

Steve Cray also mentioned, as 1 
did, that in RAM-less circuits the 
Z80 cannot use instructions that 
use the stack, so PUSHes, POP's, 
CALL'S, and interrupts can't be 
used. Although the demonstration 
program avoids that problem by 
using JUMP'S, an alternative would 
have been to stash calling ad- 
dresses in one of the other Z80 
registers such the IX or IY. Why not 
try that approach as it's a good ex- 
ercise? 

Programming style 

The last comment I got in the 
mail was about the first line of the 
program, XOR A. Since the ac- 
cumulator is loaded with a value in 
line 4 of the program, there's no 
real reason to zero it when the pro- 
gram starts. 

Now I'm the first one to admit 
that the real hallmark of slick soft- 
ware is economy. Nobody gets 
more of a kick out of hacking bytes 
off a listing than I do. And when 
you deal in the real world where 
speed and memory constraints are 
very important considerations, an 
extra few bytes or so here and 
there can mean the difference be- 
tween a working program and an 
embarrassment. 

On the other hand, good pro- 
gramming skills (or skills of any 
sort), only come about by develop- 
ing good habits, such as zeroing a 
register at the beginning of a rou- 
tine, or preserving the environ- 
ment before jumping to a sub- 
routine. Unfortunately, habitual 
operations like those can't be ap- 
plied blindly. Our XOR A doesn't 
hurt operation of the program, but 
it is unnecessary and can be de- 
leted if you wish. 

In our original discussion of the 
program, I stated Crossblatt's 
Fourth Law: You have to know the 
rules to break the rules. Let's put 
that another way: In the beginning 
you do it by the book, and when 
you think you know the book, you 
want to throw it out the window. 
But then again, it's probably better 
not to. R-E 



ANTIQUE RADIO 



continued from page 91 



could end up with twice as much 
hum. To determine whether the 
hum bucking coil is operating, just 
bypass it with a piece of insulated 
wire. If the hum level increases, 
the coil is working. However, if the 
hum level decreases, check for a 
reversed connection. 

While we try to maintain the au- 
thenticity of our antique radios, 
sometimes we have to use not- 
quite-original replacements. For 
example, you might have to re- 
place a dynamic speaker that is 
beyond repair with a PM speaker. 
You can connect the voice coil of 
the PM unit directly to the output 
transformer. You don't have to 
worry about the hum bucking coil, 
but you may have to connect a re- 
sistor or a choke to the point 
where the field coil was wired. As 
mentioned above, some chassis 
allow you to use a PM speaker just 
by disconnecting the field coil 
leads. Check your schematic. 

If you're troubleshooting an AC/ 
DC radio, in which the output 
plate current flows through the fil- 
ament of the pilot lamp, you can 
spot an open voice coil (or a bad 
solder connection) by watching 
the pilot lamp. With the volume 
turned up full, the light should 
flicker when you tune in a strong 
station. That's due to varying plate 
current flowing through the pilot 
lamp. If it flickers, but you get no 
sound output, disconnect one 
speaker lead and check the con- 
tinuity of the voice coil. If there's 
no continuity, find the cause as de- 
scribed above. 

Otherwise, the voice-coil may 
be off-center. Reconnect the 
speaker and then apply light finger 
pressure around the inside of the 
speaker cone. If the problem is an 
off-center voice coil, as you move 
your fingers around the cone, at 
some point you should hear a 
scratching noise. If there's no way 
to adjust the position of the coil, 
you'll have to replace the speaker. 

Wrapping up 

That's all for speakers and head- 
phones; next time we'll discuss 
early radio gadgets and trends in 
cabinet design. R-E 




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J 93 



STUNCUN 



continued from page 43 



board is shown in "PC Service;" alter- 
natively, a PC board can be purchased 
from the source mentioned in the Parts 
List. If you build the circuit on a per- 
fboard. Follow our parts layout closely; 
otherwise you may have problems with 
arcing. 

Due to the critical nature of the three 
transformers, we are not providing details 
on winding them. They are available from 
the source mentioned in the Parts List. 

Referring to the parts-placement di- 
agram in Fig. 2, and the photos in Fig. 3 
and Fig. 4, mount all components except 
C2, Tl, T2, and T3 on your board. Note 
that several components mount on the foil 
side of the PC board: CI, D7. and Jl. Do 
not install those parts yet either. 

After all components (except those 
mentioned above) are installed, check 
your work very carefully, especially 
D1-D6, Rl. and R3. because Tl will be 
installed above them, and there will be no 
chance to correct errors later. After you're 
absolutely sure that they're installed cor- 
rectly, install Tl with the black mark on 
the windings mounted toward C2. 

Foil-side components 

One of J 1 "s tabs shares a hole on the PC 
board with resistor R8. which should be 



mounted already. Solder the lab of J I that 
corresponds to the tip (not the barrel) of an 
inserted plug to the indicated pad. Then 
mount CI and D7. Last, solder a l 3 /4-inch 
piece of 18-gauge wire to the barrel pin of 
J I , and connect the opposite end of that 
wire to the appropriate pad beneath SI, 
the fire switch. 

Preliminary check-out 

WARNING: While measuring volt- 
ages and currents, keep your face, 
hands, and all metallic objects away 
from the high -voltage end of the stun 
gun. If if you want to prod a compo- 
nent, use a non-conductive rod such as 
a plastic TV alignment tool. High volt- 
age behaves very differently than low 
voltage. Any material that retains 
moisture can serve as a discharge path. 
THAT INCLUDES WOOD! Also, nev- 
er work on or use the unit when your 
hands are wet. 

Connect a voltmeter (set to a 1 000- volt 
DC range) to ground and to the output of 
the D3-D6 diode bridge. Then power up 
the circuit using either a freshly-charged 
battery or an external supply capable of 
delivering 9.8 volts at one amp. If every- 
thing is working properly, you should 
measure about 400- volts DC at the output 
of the bridge when you press SI. 

If you don't measure that voltage, con- 
nect an osci Iloscope to the col lector of Ql 
or Q2, You should see a squarewave with a 



period of about 100 p.s. If that waveform is 
not present, the switching circuit is not 
operating correctly. Hemove power and 
check your wiring again. Do not debug 
the circuit with a buttery connected! 

Resistor R6 controls the rate at which 
the UJT (Q3) discharges, and R3 controls 
the rate at which C2 charges. You can 
experiment with the values of those com- 
ponents if you are not satisfied with the 
circuit's high-voltage output. R3 can vary 
from 2.2 to 4.7K. You can also experi- 
ment with the value of C2. See Table 1 . 

After the circuit is operating correctly, 
attach Jl to the board with high-voltage 
potting compound or RTV. And before 
you mount the circuit in a case, make sure 
there's no arcing on the PC board. If there 
is, you can stop it with a liberal applica- 
tion of RTV, paraffin, or epoxy. 

Conclusion 

The stun gun's discharge is very im- 
pressive. The spark is highly visible and 
each discharge produces a sharp, resound- 
ing crack. The circuit can teach you much 
about voltage-multiplying circuits and 
power supply design. But don't ever for- 
get that the stun gun is not a toy. It can 
cause much damage to both you and 
others. Never leave it lying around where 
children, pets, or anyone unfamiliar with 
how to use it can handle it. It's a good idea 
to remove the battery before storing the 
stun gun. Above all; be careful! R-E 



BRAINSTORM 



continued from page 62 



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O 

£ 

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LU 

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no additional information, as it is indi- 
cated in the schematic; instead, it would 
only clutter up the chassis drawing. 

Circuit board and schematic 

Many projects begin with a vague idea 
for a device followed by some rough cir- 
cuit sketches. That's OK for the diddle 
stage, but when its time to generate the 
schematic, the diagram that will control 
the building stage of the project, the draw- 
ing must be exact and complete. 

Once you've finished the schematic, 
you need to design the circuit-board 
layout. As you're no doubt aware, when 
you draw a schematic, the symbols used 
bear no relationship to the actual size of 
the components themselves. Thus, while 
a resistor and capacitor may appear to 
occupy areas that are roughly equal, in 
reality the resistor may be only a fraction 
of the size of the capacitor, especially if 
the capacitor is a large electrolytic. To be 
sure that you've allowed sufficient space 
for each component in your design, use 
the actual parts and lay them out on an 
actual-size drawing of the circuit board. 
That is especially important when design- 



ing PC-board layouts. See "Designing 
Double-Sided Printed Circuit Boards," in 
the September 1985 issue of Radio-Elec- 
tronics for tips on laying out complicated 
circuitry. The circuit-board drawing 
should include identification of the con- 
nection points to any off- board compo- 
nents. 

Procedure 

You've prepared the paperwork, and 
you've assembled a kit with all of the 
parts. Now, you're ready to put the circuit 
together, turn it on. and watch for smoke. 
When the building process begins, you 
switch from designer to technician, with 
your paperwork guiding you every step of 
the way. 

The following step-by-step procedure 
applies the paperwork to the construction 
job, and covers initial assembly to 
finished product. Steps 1 and 2 cover 
breadboarding individual circuits for de- 
sign debugging, and will be repeated until 
each circuit works on the experimenter's 
solderless breadboard. Once the circuit 
operates correctly, final assembly requires 
repeating steps 1 and 2 to rebuild the cir- 
cuit in its final form. 

Step 1 — Mount the components on 
your circuit board (solderless experi- 
menter, perforated, wire wrap, or etched) 
using the circuit-board drawing as a 



guide. 

Step 2 — Do the wiring. When using 
wire-wrap or point-to-point techniques, 
as each connection is made, trace over the 
appropriate line on the schematic using a 
colored pencil. 

For PC boards, the same technique 
should be followed, but is should be done 
while you are designing the board. As a 
trace is laid down, the line or lines on the 
schematic should be traced over. 

Completely test the board using a tem- 
porary rig to mount any off-board parts. 
When the circuit passes all of your tests, 
it's ready for installation. 

Step 3 — Install the panel-mounted 
parts. 

Step 4 — Install the circuit board or 
boards. 

Step 5 — Wire the chassis, 
Keep the wiring as short and as neat as 
possible. Use wiring ties, cable clamps, 
etc. 

Step 6 — Apply power. If you've been 
very careful, and followed the steps we've 
shown you, the odds of getting a correctly 
working circuit the first time are greatly 
improved. Of course, they are not. 

Fortunately, if you've done your paper- 
work properly, you will have a paper trail 
to follow if you run into trouble. Very 
often that trail will lead you directly to the 
cause of your problem. R-E 



94 



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HI-FI speaker systems, kits and speaker compo- 
nents from the world's finest manufacturers. For be- 
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SPEAKERS, Box 7462R Denver, CO 80207, 
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6032 infrared tubes (tested and guaranteed), in- 
frared kits, complete line of engineering and sur- 
veillance viewers. IR SCIENTIFIC, INC., Sox 110. 
Carlisle. MA 01741 (617) 667-7110 

JERROLD gated pulse theory. Twelve information 
packed pages covering Dl and DIC converter opera- 
tion Includes introduction to trimode system. $6.95. 
ELEPHANT ELECTRONICS INC., Box 41865-J. 
Phoenix, AZ 85080 (602) 561-1973 

SATELLITE descrambling Latest method — in- 
cluding digital audio descrambling. $10.95. Design 
manual for constructing parabolic satellite dish 
antennas. $9.95 CABLETRONICS, Box 30502RE. 
Bethesda, MD 20814. 

FM Transmitter Kit, matchbox size, super sound 
sensitivity, board, parts, easy eductional instruc- 
tions. $19.95. PTS, Box 1951. Fort Worth, TX 76101. 

PHONE tap info automatic on.'off control for cas- 
sette recording phone conversations $3.95. BLED- 
SOE, 135 Cupp Dr, Central Point, OR 97502, 

DESCRAMBLER Plans $4.95 constructed easily 
thousands in use. CAREER ENTERPRISES, PO 
Box 3263, Bridgeport, CT 06605 0263. 

CURCUIT boards, Kits, and Assemblies for QST 
Articles. For info SASE to: A&A Engineering, 7970 
Orchid Dr. Buena Park. CA 90620. (714} 521 4160. 



CB MODIFICATIONS 



Increase channels, range, privacyl We specialize 
in frequency expanders, speech processors, FM 
converters, PLL & slider tficks. how-to bonks, 
plans, kits. Expert mail-in repairs & conversions. 
16-page catalog $2. Our 11th year! 



CSC INTERNATIONAL. P.O. BOX 31500RE. 
PHOENIX, AZ 85046 



EDUCATION & INSTRUCTION 

F.C.C. Commercial General Radiotelephone Li- 
cense. Electronics home study. Fast, inexpensive! 
"Free" details. COMMAND, D-176, Box £223, San 
Francisco, CA 94126. 



COMPREHENSIVE EVALUATION 
and ADVISORY SERVICE 

Fw provisional ilictronle ttchnlclsiu by pnstipu; 

NON-PROFIT irgiiiiiitnn. Earn University Degree 

i.RalKlorj oi Mssfesi through Horn Study! Ml given lor 

previous sctooling and proleisimal uperiincc Upgrade your 

statu and lift-style. 

CONTINENTAL EDUCATION ASSOCIATES 

P.O. Box 1197 - Chimptaln, NY 1 2919-11 97 




COMPUTER repair career training in 5 months by 
aceredited Florida electronics school. Lifetime 
placement. Financial assistance if qualified. Call 
SYSTEMS TECHNOLOGY INSTITUTE. 

(305)331-2840. 

SPEECH synthesis manual. Build projects that talk 
back. For everything you need to know about creat- 
ing human like speech and robot talk, send $12.95 
to: J&J ENTERPRISES, 3510 North 72nd Street, 
Omaha, NE 68134. 



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Get into Telecommunications 
Installation and Repair 

Learn at home in spare time. Telecommunications repair- 
ers work on telephone, telegraph, computer networks! 
Home-study course shows you what to cib, how to do in 
Books, manuals, tool kit included with course. Be ready far 
money- rrx3king Job In [ust o few monihs. Send tor FREE 
FACTS! School of Telecommunications 

925 Oak St., Dept. DE086. Scronton, PA 18508. ,„ 



CABLE TV Secrets— the outlaw publication the ca- 
ble companies tried to ban. HBO, Movie Channel, 
Showtime, descramblers, converters, etc. Sup- 
pliers list included $8.95. CABLE FACTS, Box 711- 
R, Ffctaskala. Ohio 43062. 

CABLE TV Source Book— a complete listing of sup- 
pliers for hard-to-find converters, descramblers, 
technical information, schematics and much much 
more. Full refund if not satisfied. Send $4.95 to 
CABLE, Box 12505-R. Columbus, OH 43212. 

SATELLITE Deserambler Schematics: Oak Orion 
PD-400C $20.00; VideoCipherll $20.00 Vid- 
eoCipherll Patent $15.00; actual VideoCipherll de- 
scrambler $550.00; acutal Oak Sigma deserambler 
$350; Catalog $5.00; send money order to ELEC- 
TRONIC PRESS, PO Box 10009. Colorado Springs, 
CO B0932. 

PATENTED optical process satellite sound system. 

For information send $3.00 to: BED1NI ELEC- 
TRONICS, PO Box 769, San Fernando. CA 91341. 



Pay TV and Satellite Descrambling 
All New 6th Edition! 



Now over 100 pages of working schematics, 
theory and "hard" information on all the major 
cable and over the air scrambling systems. 
Schematics and theory for all 4 satellite de- 
scrambling systems used currently. HBO, 
Anik-D, Fantasy, Extasy etc. New sections on 
digital audio coding and bypassing. Insider 
information included. Still the most complete 
source of descrambling info available SI 4.95. 
Satellite Systems Under S600, $11.95. MDS 
Handbook $10. Stun gun schematics $5. En- 
larged product catalog of PC's, kits and low 
cost satellite equipment S2. 



Shojiki Electronics Corp., 1327R 
Niagara St., Niagara Falls, NY 
143D3. COO's 716-284-2163 



59 degree brand name LNA's! LNB's! Ku-Band 
LNB's! Discount pricing! Send stamped envelope: 
LNA, 201 E Southern, Suite 1O0F, Tempe, AZ 
85232. 

SATELLITE systems $349.00, catalog $3.00. Also: 
KU; Exports; descrambiers.STARLINK, INC., 
2603-1 6R Artie, Huntsville. AL 35805. 

"TRIPLE-X" Satellite TV Deserambler (Non Ad- 
dressable). XXX Adult Movies, Fully Assembled. 
$225. N AS-SAT, Box 5261, Long Beach, CA 90805, 
(213)631-3552. 

DISCOUNT CATV Converters,' Decoders and video 
accessories. Free information. EASY VIEW. PO 
Box 221B, Arlington Heights, IL 60006 (312) 952 
8504 ask for Rudy Valentine. 

FEELING Scrambled? Here's the answer! Micro- 
wave TV receivers 20" dish system (1.9 2.7GHz). 
Lifetime warranty. Send $89.95 to: K&S ELEC- 
TRONICS. Box 34522RE. Phoenix, AZ 85067. $2. 
credit on phone orders (602) 230 0640. Call now for 
same day shipping! Dealer rates' brochure SASE 
VISA/MC/COD'S 

SECRET "Hidden Signals" on satellite TV are easily 
decoded. New 179 page book covers theory and 
describes equipment needed. $19.95 plus $2 P&H. 
ELEPHANT ELECTRONICS INC, Box 41865-J. 
Phoenix, AZ 85080 (602) 581 1973. 

SATELLITE owners unlock your videocipher de- 
scrambler, parts and plans $35.00 I (305) 752 
9202. 

BUILD your own satellite system and save! Instruc- 
tions, schematics, parts! Send stamped envelope: 
XANDI, Box 25647, Dept. 21E, Tempe. AZ 85282, 



WANTED 

INVENTORS! AIM wants— ideas, inventions, new 
products, improvements on existing products. We 
present ideas to manufacturers. Confidentiality 
guaranteed. Call toll free (1-800)225-5800 for infor- 
mation kit. 

INVENTIONS, ideas, new products wanted! Indus- 
try presentation/national exposition. Call free 
(1-800)528-6050. Canada, 1-800-528-6060. X831. 



TURNTABLE, transcription, 16 inch. BLACKARD. 
Route 2, Box 222, Trinity, AL 35673 

SOLVE new software protection code: earn 59,000. 
immediately! Sample $1.00. CODE RESEARCH, 
Box 841, Cornelius, OR 97113 



BUSINESS OPPORTUNITIES 

MECHANICALLY inclined individuals desiring 
ownership of small electronics manufacturing busi- 
ness—without investment. Write: BUSINESSES, 
92-R. Brighton 11th, Brooklyn. NY 11235. 

YOUR own radio station! AM, FM. TV, Cable, Li- 
censed/unlicensed. BROADCASTING, Box 130-F9 
Paradise, CA 95969. 

EASY, one man, hi-profit CRT rebuilding equip- 
ment. C.R.T., 1909 Louise, Crystalake, IL. 60014 
(815)459-0666. 

PROJECTION TV . . . Make $$$'s assembling proj- 
ectors . . . easy . . . results comparable to $2,500. 
projectors . . . Your total cost less than $30.00 . . . 
plans, 8" lens and dealers information $20.50 
. . . illustrated information free . . . MACROCOMA- 
GAX, Washington Crossing, Pennsylvania 18977. 
Crediteard orders 24 hours (215) 736-2880. 

YOUR eleclronics knowledge means honest part 
time income. Write YOUR MARKETING, 479 Cher- 
okee Ridge. Athens, GA 30606 



ELECTRONIC 
ASSEMBLY BUSINE5S 



Slart home, spare time. Inveslmenl knowledge or 
experience unnecessary. BIG DEMAND assem- 
bling electronic devices. Sales handled by profes- 
sionals. Unusual business opportunity. 

FREE: Complete illustrated literature 

BARTA. RE-0 Box 248 
Walnul Creek Calif. 94597 



FOR SALE 



TUBES new, unused. Send self-addressed, stamp- 
ed envelope for list FALA ELECTRONICS, Box 
1376-2. Milwaukee, Wl 53201. 

LINEAR parts, tubes, tramsistors — MRF454 
$16, MRF455 $12, MRF477 $11, MRF492 $18. Cat- 
alog. RFPC, Box 700, San Marcos, CA 92069 
(619)744-0728. 

RESTRICTED technical information: Electronic 
surveillance, schematics, locksmifhing, covert sci- 
ences, hacking, etc. Huge selection. Free bro- 
chure. MENTOR-Z, 1 35-53 No. Blvd., Flushing, NY 
11354. 

OLDTIME radio programs on high quality tapes. 
Comedy! Adventure! Music! Free catalog. CARL F. 

FROELICH, Heritage Farm, New Freedom, PA 
17349. 

TV tunable notch filters, free brochure. D.K. VIDEO, 
Box 63/6025, Margate, FL 33063 (305)752-9202. 

TEST equipment, reconditioned. For sale. $1.25 for 
catalog. WALTER'S, 2697 Nickel, San Pablo, CA 
94806 (415)724-0587. 

LASERS and nightvision surplus components. Free 
catalog, M.J. NEAL COMPANY, 6672 Mallard Ct„ 
Orient, OH 43146. 

TI-99/4A software/hardware bargains. Hard to find 
items. Huge selection. Fast service. Free catalog. 
DYNA, Box 690, Hicksville, NY 11801. 

FREE Adapter (Limited offer) with Assort- 
ment #1Q3-cunsisting of Toko Coils 
144LY-120K, 520 HN-3000023, BKAN- 
K555AXX (2); PCB; Transistors 2N3904 (2), 
BFQ85 (sub); IC's7812, 74123, MC1330A1P; 
Diodes 1N914, 1N5231B. Only $25.00 10% 
discount for 5 or more. Shipping. $3.00/ 
order MC/Visa/COD. Toll free 1-800-821- 
5226 Ext. 426 (orders). Jim Rhodes, Inc., 
1025 Ransome Lane, Kingsport, TN 37660. 

TUBES, name brands, new, 80% off list. KIR BY, 
298 West Carmel Drive, Carmel. IN 46032. 



96 



CABLE-TV converters and descramblers. Low 
prices, quality merchandise, we ship C.O.D. Send 
$2.00 for catalog. CABLETRON1CS UNLIMITED, 
P.O. Box 266, South Weymouth, MA 02190. (617) 
871-6500. 

D ESC RAMBLER plans for Jerrold. Theory, sche- 
matic, parts list, waveforms. For speedy delivery 
send S10.00 cash or money order. BAY STATE 
ELECTRONICS, PO. Box 63. Accord. MA 02018. 



ml 



Quality Microwave TV Antennas 



Mulll-Channel 1 9 to 2.7 GHz 
AticiB Gain True Parabolic 20 Inch Dish 
Cr-MT.jii.--iy System $99.95 (plus shipping} 
Dealership*, Qly. Pricing, Replacement Parts 

PnllllDs-TBCh Electronics 

P.O. Box 8S33 • ScdttHSafc, IZ 85252 
LIFETIME (602)947-7700 1*300 Crednall phon-ciilErs': 
WA B R A NTV MnlerCard • Visa ■ COD J 



INDIVIDUAL Photofact-folders #1 to #1400. $3,00 
postpaid. LOEB, 414 Chestnut Lane, East Meadow, 
NY 11554 

CORDLESS-phone interference? We've got the an- 
swer. Have a radar speeding ticket? We can help. 
Home phone extension in your car? You can have it. 
50-page color catalog airmailed $3.00, DBE, P.O. 
Drawer G, Waikiki, Hf96830. 

ELECTRON tubes — radio, TV S industrial types — 
huge inventory. Call toll free (800-221-5802) or write 
Box ESC, TRANSLETERONIC, INC., 1365 39th 
St., Brooklyn, NY 11218, (718-633-2800). 

WHOLESALE catalog of unusual money making 
electronic items. Dealers wanted. Rush $1. 
CROSLEY (A), Box 840, Champlain, NY 12919. 

WANTED: Western Electric, RCA, Marantz, Mcin- 
tosh, Telefunken, Dynaco, Altec, EV, Tubes, ampli- 
fiers, speakers (713)728-4343, MAURY, 11122 
Atwell,Houston, TX 77096. 



A SINGER'S DREAM! 



• 4p ' i 



REMOVES VOCALS FROM RECORDS! 

Now You can sing with the world's best bands! 
The Thompson Vocal Eliminator can remove 
most or virtually all of a lead vocal from a standard 
stereo record and leave the background! 

Write or call for a free brochure and demo record. 

LT Sound, Dept. R-l, P.O. Box 338. 
Stone mountain, CA 30086 (404)493-1258 



FREE Transistors: Sample of PN222 and 2N3904 
with our Catalog of Budget Priced Electronics 
Components for hobbyists and industry. Send 
$2.00 P&H (refundable) BUDGET ELECTRONICS, 

Box 1477, Moreno Valley, CA 92368(714)653-1663. 

CATALOG: Cable converters and descramblers. 
N12 Minicode $98, Jerrold 400 S99. MLD 1200 
S99. Pulse descrambler kit (assembles in half 
hour) 379, built $120. Satellite descrambler kit 
$119, built $190. Also surplus components, hob- 
by kits. Send S1. M J INDUSTRY, Box 531, Bronx, 
NY 10461. 

BUGGED? Wiretapped? Find out fast. Counter- 
measures equipment catalog $1. CAPRI ELEC- 
TRONICS, Route 1R, Canon, GA 30520. 

WHOLESALE car-radio computer telephone audio 
video acessories antenna catalog (718)897-0509 
D&WR. 68-12 110th St., Hushing, NY 11375. 

SB3 descrambler parts to construct project in 
Feb.'84 Radio-Electronics. $49.95 (Dealer inquires 
invited). CROSLEY, Box 840, Champlain, NY 
12919. 

WORLDS best channel 3 notch filter. $39.95. (Deal- 
er inquires invited). CROSLEY (A), Box 840, Cham- 
plain. NY 12919. 

SCIENTIFIC Atlanta. Stand alone descrambler. 
Priced under $100. Details $2. DIGITEK, Box 195, 

Levittown, PA 19059. 



CABLE-TV 




BONANZA! 



ITEM 



RCA 36 CHANNEL CONVERTER {CH. 3 OUTPUT ONLY) 



PIONEER WIRELESS CONVERTER (OUR BEST BUY) 



LCC-S8 WIRELESS CONVERTER 



JERROLD 450 WIRELESS CONVERTER (CH. 3 OUTPUT ONLY) 



SB ADD-ON UNIT 



BRAND NEW — UNIT FOR SCIENTIFIC ATLANTA 



MINICODE (N-12) 



MINICODE (N-12) VARISYNC 



MINICODE VARISYNC W/AUTO ON-OFF 



M-35 B (CH. 3 OUTPUT ONLY) 



M-35 B W/AUTO ON-OFF (CALL FOR AVAILABILITY) 



MLD- 1200-3 (CALL IF CH. 2 OUTPUT) 



INTERFERENCE FILTERS — CH. 3 



JERROLD 400 OR 450 REMOTE CONTROLLER 



ZENITH SSAVI CABLE READY (DEALER PRICE BASED ON 5 UNITS) 



SINGLE 
UNIT 
PRICE 



29.95 



88,95 



92.95 



105.95 



DEALER 
10-UNIT 

PRICE 



18.00 ea. 



72.00 ea. 



76.00 ea. 



90.00 ea 



109.95 58.00 ea. 



Call for specifics 



109.95 58.00 ea 



119.95 



179.95 



139.95 



199.95 



109.95 



24.95 



29,95 



225.00 



62.00 ea 



115.00 ea 



70,00 ea 



125,00 ea 



58.00 ea 



14,00 ea 



18.00 ea 



185.00 ea 



SPECIFY CHANNEL 2 or 3 OUTPUT 



Other products available — Please Call 



Quantity 


Item 


Oulpul 
Channel 


Price 

Each 


TOTAL 
PRICE 
































































SUBTOTAL 




from shipping any cable descrambling unit 
to anyone residing in the state of California, 

Prices subject to change without notice 


Shipping Add 
$3.00 per unit 




COD& Credit 
Cards — Add 5% 




PI PiRF PRIWT 


TOTAL 





Name 



Address 
State 



-City. 



□ Cashier's Check 

Acct S 

Signature 



. Zip 

□ Money Order 



. Phone Number ( ) 

□ COD □ Visa 
Exp. Date 



D Mastercard 



FOR OUR RECORDS: 

DECLARATION OF AUTHORIZED USE — I. the undersigned, do hereby declare under 
penalty of perjury that all products purchased, now and in the future, will only be used on cable 
TV systems with proper authorization from local officials or cable company officials in 
accordance with all applicable federal and state laws. 



Dated:. 



.Signed:. 



Pacific Cable Company, Inc. 

7325 1 /z RESEDA BLVD., DEPT, R-9 • RESEDA, CA 91335 
(818)716-5914 ■ No Collect Calls • (818)716-5140 



IMPORTANT: WHEN CALLING FOR INFORMATION 

Please have the make and model # of the equipment used in your area. Thank You 



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97 



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BURGLAR ALARM 



continued from page 44 



Begin by drilling holes for the two 
LED's and the key switch; also drill two 
mounting holes. Be careful, as a neat, 
"professional" looking job will help en- 
hance the effect. Next, secure a "C'-cell 
battery holder to the panel using RTV 
adhesive; the holder should be located just 
below the holes for the LED's. Then 
mount the key switch in the appropriate 
hole. Wire the switch and the battery 
holder to the appropriate points on the 
board, keeping lead lengths as short as 
possible. Bend the LED's 90° so that they 
are parallel with the board. Position the 
LED's in the holes you previously drilled 
for that purpose so that they protrude 
about Vs inch. Finish up by securing the 
board to the top of the battery holder with 
a piece of double sided tape. Fig. 3 shows 
how it should look. 

The unit can be installed just about any- 
where. We suggest mounting it in your 
door frame for a professional look. 

Although the circuit doesn't actually 
do anything, you should make it a habit to 
"arm" and "disarm" it as appropriate. 
That little bit of theater will help convince 
a burglar who is "casing" your home that 
it is indeed protected as advertised- R-E 





>H'JW 



PLAKS — All Parts Available in Stock 
LC5 BURNING CUTTIG C02 LASER . . $20,00 

RUB3 RUBY LASER RAY PISTOL 20.00 

BTC5 1.5 MILLION VOLT TESLA COIL. . . 15.00 
PTG1 PLASMA TORNADO GENERATOR 10.00 

G.RA1— GRAVITY GENERATOR 10.00 

MAGNETIC CANNON PROJECTOR 10.00 



I KITS— Includes Plans and Parts 

|« LHC2K SIMULATED RED/GRN/YEL LIGHT 

LASER 34.50 

I • BTC3K 250.000 VOLT TESLA COIL . ... 159.50 

• 10G1K ION RAY GUN 109.50 

I* PSP3K PHASOR SHOCK WAVE PISTOL 49.50 

STG1K— STUN/PARALYZING GUN 39.50 

I* INF1K INFINITY TRANSMITTER 134.50 

|* MFT1K 2-3 MILE RANGE FM VOICE 

XMTR PC BOARD 49.50 



ASSEMBLED AND TESTED PRODUCTS 

| • LGU30 RED 1MW PORTABLE HENE 

LASER 349.50 

I • TCL30 SOLID STATE TESLA COIL 35KV 84.50 

I • IPG50 POCKET PAIN FIELD GENERATOR 64.50 
BLS10 BLASTER DEFENSE WEAPON . . . 39.50 
ITM10— 10QKV SHOCK AND STUN GUN 99.50 

I • PPF10 PHASOR PAIN FIELD PORTABLE 249.50 

• SNP20 SECURITY PHONE LISTENER 99.50 

• CATALOG CONTAINING DESCRIPTIONS OF 
ABOVE PLUS HUNDREDS MORE AVAILABLE FOR 
S1.00 OR INCLUDED FREE WITH ALL ABOVE OR- 
DERS. 

PLEASE INCLUDE S3.00 PH ON ALL KITS AND 
PRODUCTS PLANS ARE POSTAGE PAID. SEND 
CHECK. M0, VISA, MC TO: 



INFORMATION UNLIMITED 

P.O. BOX 716. DEPT. N1 AMHERST. NH 03031 



SCIENTIFIC Atlanta cable equipment! We have 
8550s 8500s complete cable boxes. See all the 
channels! All units are just waiting for you. De- 
scramblers and Remotes ADVANCED TECH- 
NOLOGY SYSTEMS, Box 316, Auburn. MA 01501. 
1617)832-2339. 

SPECTACULAR strobe light chasers, stroboscope 
devices, Helium-Neon Laser components, scien- 
tific items, more! Free catalog. ALLEGRO ELEC- 
TRONIC SYSTEMS, #3R Mine Mountain, Cornwall 
Bridge, CT 06754. 

CHIP Checker tests/identifies: 54/74 TTL, 4000 
CMOS, 54/74 CMOS, Two 24 pin ZIP sockets han- 
dle .3" and .6" wide chips. For C128 and C64. $129 
plus $3.50 s&h, DUNE SYSTEMS, 2603 Willa Dr., 
St. Joseph, Ml 49085. (616)983-2352. 

TUBES: "oldest," latest". Parts, components, sche- 
matics. SASE for list. STEINMETZ, 7519 
Maplewood Ave., RE., Hammond, IN., 46324. 

ELECTRONICS. $1.50 brings flyer, grab bag. LYNN 
JOHNSON, 2221 The Alameda #176. Santa Clara. 
CA 95050. 

BATTERIES NiCad, sealed lead acid, and more 
Irom national brands such as Panasonic, Eagle- 
Picher, and others. Write or call for listing. DC 
Power, Inc., 1213 Old Colony Rd„ Wallingford. CT 
06492, (203)237-2292. ___ 

ANTIQUE radio hobbyists — 20 page catalog of 
tubes, parts, and literature for radio restoration. 
Send $2.00 to ANTIQUE ELECTRONIC SUPPLY, 
68S W. First St., Tempe, AZ 85281 

CABLE- TV converters and equipment. Plans and 
parts. Build or buy. Free information. C&D ELEC- 
TRONICS, PC Box 1402, Dept. RE, Hope, AR 
71801. 

35 - 70% saving — bargan catalog for 39 cents 
stamp APEX ELECTRONICS MOD, 8909 San Fer- 
nando, Sun Valley, CA 91352. 

TURBO circuit analysis Generates matrix equa- 
tions for AC, DC and Transient Analysis. Source 
code for Worst Case, Plots. Requires MS-DOS and 
Turbo Pascal or FORTRAN. V1SA/MC. $149. 
CLIFFORD VANDER YACHT, Computer Consul- 
tant, 3778 Hitching Post Road. Jackson. Ml 49201, 
(517)782-2297. 

HIGH gain de scram biers, CRT automatic dimmer, 
SCR Tester, plus other unusual electronic devices. 
Send $3. lor info. RB ELECTRONICS ENGINEER- 
ING, PO Box 643 Kalamazoo. Ml. 49005. 

PING-Pong 8/section light chaser controller 
$34.95. Strobe light S9.95. (Perfect disco setup). Ve- 
hicle alarm-current sensor $14.95. ADVANCED 
CONCEPTS, 38575 9th St. East, Suite 264. Palm- 
dale, CA 93550 (305) 273 6449 

IS it true.. Jeeps for $44. through the Government? 
Call for facts! 1-312-742-1142 Ext. 4673. 

CABLE TV converters manual and wireless Jerrold 
DRZ DRX Philips volume converters. REDCOAT 
ELECTRONICS, PO Box 504, Jamaica, NY 11475. 

(718) 459-5088. 

SCIENTIFIC Atlanta stand alone— 8500 series 
(Original Units}, remote control. Fully guaranteed 
$250. N.A.S., (213) 631 3552. 

VIDEO scrambling techniques, the original "secret 
manual" covers sinewave. gatedpulse, and SSAVl 
systems. 56 pages of solid, useful, legible informa- 
tion, only $14.95. ELEPHANT ELECTRONICS 
INC., Box 41865-J, Phoenix, AZ 85080 (602) 581 
1973. 

ELECTROCALC can do your electronics calcula- 
tions: Crossover, resonance etc. For Commodore 
C-64 or 128 (specify). $19.95 post paid. NOVA- 
SOFT, Route 1, Box 107B, Kinston, NC 28501. 

MODEL PS-320 Triple Supply. 5V, 1.5A. ±15V, 
0.7A. 8" v- 6" x 3" detachable power cord. Contact 
RCB ENGINEERING PRODUCTS, Box 143, Hano- 
ver, MD 21076 (301) 796 3099. 

UNIDEN Exports radio and amps send $5. WASH- 
INGTON ENTP., 1725 North Bond Street, Balto.. 
MD 21213. 

ONE picture tube rebuilding machine. One man op- 
eration. Buyer must pick up in El Paso, $5500. 
ADAMSON 3204 Stone Edge, El Paso, TX 79904 
(915) 755 8942. 

ELECTROLYTICS: 48,000n.F 40V. Spragues best 
computer "Extralytic". New w/specs, $4.95 2'$7.50 
WALZ. 3327 Allendorf, Pittsburgh, PA 15204. 



SURPLUS military/commercial Test and communi- 
cations equipment — 1986 catalog. Send $1 MIL- 
COM EXCHANGE ELECTRONICS, Box 982-RE. 

Orange Park, FL 32067-0982. 

CLONE kits, modems, hard drive kits, disk drives, 
diskettes and printers, memory, and ICs. Distributor 
pricing to end users and dealers. For catalog call 
1-800-833-2600. In Ohio call 513-531-8866. Free 
shipping. 

FREE electronics parts. All sorts, for inventors, de- 
signers, ex peri mentors. How and where to get 
them. No exaggeration. Send single fee $6.95 to 
AMERICAN TRANS-GLOBAL, Box 7033, Hunt- 
ingon, WV 25775. 



REEL-TO-REEL TAPES 

AMPEX professional series open reel tape. 1800-or 
2400-feet on 7-inch reels. Used once. Case of 40. 
$45,00. 10 W x 3600 feel and cassettes available. 
MasterCard, Visa. VALTECH ELECTRONICS, Box 
6-RE, Richboro, PA 18954. (215) 322-4866. 



DO IT YOURSELF REPAIR 

NEW... repair any TV,. .easy Anyone can do it. 
Write. RESEARCH, Rt3 Box 601BR Colville. WA 
99114, 



PRINTED-CIRCUIT BOARDS 

P CB 1 5 ce nts sq - i n . f ree dri Hi ng . Gu antity d i scou nts. 
Professional work. INTERNATIONAL ENTER- 
PRISE, 6452 Hazelcircle, Simivalley. CA 93063. 



INVENTORS 



INVENTORS! Can you patent and profit from your 
idea? Call AMERICAN INVENTORS CORPORA- 
TION for free information. Over a decade of service. 
(1-800)338-5656. In Massachusetts or Canada call 
(413) 568-3753. 



PRINTED-CIRCUIT BOARDS 

FAST service. Guaranteed lowest quotes. Average 
$0.12 / inch (FR-4),Single Sided I multilayered 
boards. Plated thru holes. Any quantity. Send speci- 
lications/call for quotes and details. CATALOG of 
electronics components and projects — send 
SASE— T.O.R.C.C.C, Box 47148, Chicago, 60647, 
(312)-342-9171. 

PRINTED-circuit boards and artwork design cad/ 
cam plated through holes. Competitive pricing. EX- 
PRESS CIRCUITS, 314 Cothren Street, PO Box 58, 
Wilkesboro. NC 28697 (919) 667-2100. 



CABLE-TV 



DEALERS wanted: channel 2,3, and 4 notch filters. 
Money back guarantee. Send S15.00 for sample 
and quantity price list. Specify channel(s). GARY 
KURTZ, Box 291394. Davie, FL 33329. 



SPEAKER REPAIR 

SPEAKER reconing— radio, hi-fi, musical instrument. 
All work guaranteed SS1 1925 Charlwell, Ft. Wayne, 
IN 46816 219-42-MUSIC. 



THIS IS A BOLDFACE EXPANDED AD. If you 
like this format, request it. Your cost is 
$3.75 per word, plus 45% for the boldface 
and tint background. 






WRITE FOR 



McGEE'S 



SPEAKER & ELECTRONICS CATALOG 

1001 BARGAINS IN SPEAKERS 

toll free 1-800-346-2433 for ordering only, 

1901 MCGEE STREET KANSAS CITY, MO. 64*08 



98 



Radio /hack Part/ Place 



TM 



'87 CATALOG AVAILABLE— COME GET YOUR FREE COPY 

184 Full-Color Pages ■ Hundreds of New Items and New Low Prices ■ Not Sent by Mail 



Breadboard It 




(1) Universal. Our best! Breadboard is mounted 
on a 7 x 4" "stay-put" steel base with rubber feet. 
640 plug-in points, 3 binding posts. #276-169, 19.95 

(2) Modular Breadboard Socket. 2 buses, 550 
indexed connection points. Snap together for more 
complex designs. 2Vax6" #276-174 11.95 

(3) Modular Breadboard Socket. Smaller version 
of Fig, 2. 2Vsx3 s /b" #276-175 6.95 

(4) Matching PC Board. Same layout as sockets 
for easy circuit transfer, #276-170 2.69 



Books by Forrest Mims 





(5) 



■ Easy-to-Read Schematics 

■ Parts in Stock at Radio Shack 

(5) Op Amp Mini-Notebook. Learn as you build! 
48 pages contain over 40 clever circuits using 
popular op amps such as the 741. 
#276-5011 1,49 

(6) Optoelectronics Mini-Notebook. 46 pages. 
Features a great introductory section on optical 
components. Projects range tram a simple LED 
circuit to lightwave transmitter/receiver circuits. 
#276-5012 1.49 



Voice Synthesizer Team 



Add Voice to 
Your Computer 



(7) 



mm 



9WS!p 



(7) SP025S-AL2 
Speech Synthesizer IC. 
MOS/LS1 device is easy 
to interface with nnost 
computers. With data. 
2B-pln DIP, 

#276-1784 12.95 

IS) CTS256-AL2 Text-to- 
Speech IC. Translates 
ASCII characters into 
control data for Fig. 7. 
With dale. 40-pin DIP 
#276-1786 18.95 



Fiber-Optics Components 



(9) Optical Fiber Cable. 
3-meter length of high- 
quality optical cable is 
Ideal tor experiments. 
#276-228 5.99 

(10) Emitter/Detector 
Sat, Use to send analog 
or digital signals Ihrougn 
fiber optic cable. With 
data. #276-225 . . . 4.99 




Easy-to-Use Soundmakers 

(11) Electronic Chime. IC/speaker combo produces a 
"ding-dong" sound. 12 VDC. #273-071 6.9S 

(12) 2-Tonc Pieio Buzzer. Really gets attention! Operates 
8 to 18 VDC. #273-070 B.95 

(1 3) PC-Mount Piezo Buzzer. Loud, yet consumes only 12 
milliamps al 12 VDC. #273065 2.49 



Hi-Q Ceramic Discs 



Battery Guidebook 




pF 


VDC 


Cat. No. 


2-Pack 


uF 


VDC 


Cat. No. 


2-Pack 


4.7 


50 


272-120 


.39 


.001 


500 


272-128 


.49 


47 


50 


272-121 


.39 


.0047 


500 


272-130 


.49 


100 


50 


272-123 


39 


.01 


500 


272-131 


49 


220 


50 


272-124 


.39 


.047 


50 


272-134 


.49 


470 


50 


272-125 


.39 


.1 


50 


272-135 


.49 



Helps You Select 
The Right Battery 

Learn how batteries work, 
how to recharge and test 
them, and how to choose 
the best values. Includes 
complete technical data on 
all ENERCELL 8 batteries. 
160 pages. 
#62-1396 1.99 




Resistor Kit Bargains 

(14) 



Tantalum Capacitors 



Low-Cost Panel Switches 






High Capacity in 
A Small Package 
IC Pin Spacing 
20% Tolerance 



<16> iSk 




(14) V«-Watt. 51* tolerance. 100-piece set Includes 13 pop- 
ular standard values ranging from 10 ohms to one meqohrn 
#271-308 2.79 

(1 5) Precision Metal-FHm. </<-watl, 1% tolerance 50 piece 
set includes 12 popular standard values ranging from 10 

ohms to one megohm. #271-309 2,49 



UF 


wvrjc 


Cat. No. 


Each 


uF 


WVDC 


Cat. No. 


Each 


0.1 

0.47 

1.0 


35 
35 

35 


272-1432 
272-1433 
272-1434 


.49 

.49 
.49 


2.2 

10 
22 


35 
16 
16 


272-1435 
272-1436 
272-1437 


.59 
.69 

.69. 



(16) Subm In I Toggles. 3 A at 125 VAC. '/«" mlg. hole. 

SPST. 275-612 1,69 SPOT. 275-613 . . . 1.79 

DPDT, 275-614 . . . 2.19 OPDT Center-Ofl. 275-620 ... 2,29 

(17) Submlnt SPST Momentary. Rated 0.5 amp at 125 
VAC. Normally open. Vtex 'Al Includes one red. one black. 
Vtr mtg. hole. 276-1571 Set ol 2/1.69 



Hobby Motor Bargains 




Ideal for Robotics 
Science Projects, 
Model-Making 
And Fun! 



\w 



(18) High Torque. 8300 maximum RPM, operates 
1 .5 to 3 V DC . Approxi m ately 1 ' fa " long by 1 s / 1 e" dia, 
#273-223 79* 

(19) With Brass Pulley. Built-in noise filter. Oper- 
ates 3Va to 9 VDC. #273-229 Pkg. Of 2/1.49 



Attention-Getting LEDs 



(20) 




(21 > 



(20) Super-Bright Red LED. A real breakthrough! 
Outputs 300 mcd at 20 m A yet runs cool. Point- 
source type in a clear epoxy T-1 3 /* package, 
#276-066 99* 

(21) CQX21 Blinking LED. Combines MOS driver 
IC and red LED in a T-W* package. #376-036, 1.19 



Digital Logic Probe 




The fast way to test TTL, LS and CMOS digital 
circuits. Color-coded LEDs indicate high, low or 
pulsed logic states (up to 10 MHz). Simultaneous 
ton e o u tp ut frees yo u r eyes for faster testing . 36 " 
leads with clips provide power from circuit under 
test. With instructions. #22-303 16.95 



Digital Logic Pulser 




Together, the pulser and probe make an effective 
diagnostic team for testing today's digital circuits. 
Produces single 5 us pulse or a continuous 5 Hz 
pulse train at the push of a button. Features over- 
load protection and low output impedance. With 
instructions. #22-304 17.95 



21 -Range Digital VOM 
Cut 37% 

SUPER 
SAVER! 



Reg. 
59.95 



3788 



Accuracy, ease of 
use and famous Mi- 
cro nta s quality at 
33% off! Features 
big LCD display, 
"beep" continuity 
test mode, ohms 
zero-adjust button, 
diode-check mode. 
Measures to 1000 
volts DC, 500 volts 
AC, AC/OC current 
to 200 mA. Resist- 
ance to 20 me- 
gohms. 6 3 /ax3 1 /2X 
1 a fa'! With owner's 
manual and probes. 
Requires 2 "AA" 
batteries. 
#22-191. Sale 37.88 




Over 1000 Items in stock: Binding posts, Books, Breadboards, Buzzers, Capacitors, Chokes, Clips, 
Coax, Connectors, Fuses, Hardware, ICa, Jacks, Knobs, Lamps, Multltesters, PC Boards, Plugs, 
Rectifiers, Relays, Resistors, Switches, Tools, Transformers, Transistors, Wire, Zeners, more! 



Radio /hack 

A DIVISION OF TANDY CORPORATION 

Prices apply at participating Radio Shack stores and dealers 



LO 

m 
m 
m 
so 

CO 

o> 



CIRCLE 78 ON FREE INFORMATION CARD 



99 



ygoo 



Pari No. 


Prkc 
19 


Port No. 


Price 


SN7400N 


SN7486N 


55 


SN7402N 


19 


SN74S6N. ... 


.35 


SM7404m 


.25 


SN7489N. 


. . . , 1.95 


SN7405N 


29 


SN740ONL 


39 


SM7406N 


29 


SN7493N 


35 




.26 


SN74121N 


29 


SN7408N 


.25 


SN74123N 


A9 


SN7410N 


19 


SN74125N 


.45 


SN741 4N. . . . 


45 


SN74126I>L 


.49 


SN7416N. 


35 


SN74143N. . .. 


... 3.95 


SN7417N. 


35 


SW741 50M 


.... 129 


EN7420N. 


19 


SN74154N 


125 


5N7430N. 


19 


SN7415BN. . . . 


.... 139 


SN7432N 


29 


EN741 73N. 


.76 




29 


SN74174N 


59 


SN7442N 


.45 


SN74175N 


59 


SN7445N 


£9 


SN7417GN 


39 




.78 


SN74181N. . . . 


1.9S 










SN7448N 


7B 


SN74193N 


69 


5N7472N 


38 


SN7419SN. . . . 


... . 135 


SN7473SL 


35 


SN74221N 


89 


SN7474N 


.35 


SM7J273N. . . . 


.... 1.95 


SN7475N, .... 


39 


SN74365N 


.59 


5N7476N 


35 


SN74367N. . . . 


. . .59 



74LS 



7JLS00 


19 


74LS1 65 


79 


74LSQ2. 


19 


74LS166. 


69 












25 

99 




39 


74L5Q6- 


74LS175. 


39 










74LS08. 


19 


74L5191 


A9 


74LS10. 


.19 


74LS193. 


.69 


74LS14. 


.... 39 


74LS221 


J59 


74LS27 


.... 25 


74LS240 


69 


74LS30 


19 


74US243. 


.59 


74LS32. 


.... 25 


74LS244 


69 


74LS42 


39 


74LS246, 


.79 


74LS47. 


.... 39 


74L5259. 


..... 1.19 


74LS73 


.35 


74LS273 


79 


74LS74 


25 


74LS279. .... 


39 


74LS75 


29 


74LS322. 


. , . 2.95 


74LS76. 


23 


74LS365. 


39 


74LSS5. ...... 


A9 


74LS366. 


39 




25 


74LS367. 


39 


74LS90 


39 


74LS368. 


39 


74LS93. 


39 


74LS373 


79 


74LS123. 


.49 


74LS374. .... 


79 


74LS125. 


39 


74LS393 


79 


74LS138. 


.39 


74LS590 


5.95 


74LS139. 


39 


74US624- 


1.95 




1.49 


74LS629 


249 


74US157. 


.35 


74LS640. 


sa 


74LS15a 


35 


74LSS45. 


.99 


74LS1 S3. 


.48 


741S670. 


.99 


74LS164 


.49 


7JLS688. 


1.95 











74504. 


35 


74S169. 


1J95 


74508. ..... 


.35 


74S196. 


1.49 


74510. 


29 


74S240 


1v49 




3S 


74S2+4 


1.49 


74S74. 


.49 


74S253 


...... .79 


74S85 


1.49 


74S287- 


1.69 


74566 


35 


74S288' 


1.69 


74S124. 


2.75 


74S373 


1.69 


74S174. 


79 


74S374. 


1.69 


74S175. . 


.79 


74S472* 


.... 3.49 



74ALS 



74ALS0O 


... 35 


74ALS138 


.... B9 


74ALS02 


.... 35 


74ALS174. 


B9 


74ALS04. 


.... 39 


74ALS1 75 


.... 39 






74ALS240. .... 
74ALS244 




74ALS10. 


.... 35 


.... 1.79 


74AL527 


39 


74ALS245. 


... 2.49 


74ALS30. 


.... 35 


74ALS373. .... 


.... 1 .95 


74ALS32 


.... ,39 


74ALS374. .... 


.... 1.95 


74ALS74. 


55 


74ALS57a .... 


.. .. 1.95 



74F 





59 


74P139. 


129 




65 

£9 






74FOS 


74F193. 


4.95 


74F10. 


59 


74F240- ..... 


2 49 


74F32 


£5 


74F244. 


2-49 


74F74. 


BB 


74F253 


1.79 


74F86 


69 


74F373. 


2 95 


74F138 


1.19 


74F374. 


2.95 



CD— CHIOS 



CD4001 


19 


CD40B1 


... 25 


CO4011 


1B 


CD4082 


.... 25 






CD4093 


39 


CD401 6 


29 


CD4094. 


. . . . 1.49 


CD4017. 


.49 


CD40103. 


. . . . 295 


CD401B. 


S9 


CO4503. 


49 


CD4020. 


39 


CD4510 


.... .69 


CD4024. 


.49 


CD4511 


69 


C04027 


39 


CD4S1 5 


. . . . 1 39 


CD4030. 


39 


CD4518. 


.... .79 


CQ4040, 


65 


CO4520. . , 


.... .79 


CD4049 


29 


CD4522 


.... .79 










CO4051 


.65 


CD4541 


.... .89 


CD4052. 


.65 


CD4543 ... 


.... 39 


CD4053 


35 


CD4553 


4.95 


CD4059. 


349 


C04555 


.... 89 


CD4060. 


39 


G04555. 


.... 1.95 


CO4066 


29 


CD4583. 


.... 1.19 


CD4069. 


25 


CD45S4 


... 29 


CD4070 


29 


CD4585. 


76 


CD4071 


..... 25 


MC14411 


... 9.95 


CO4072 


2S 


MC14490P ... 


4.49 


CD4076. 


69 


MC1 4572. 


.... 39 



CUSTOM COMMODORE CHIPS 

For VIC-20, C-64 and C-128 Personal Computers 



Part No. 


Price 


PnrtNo. 


Price 


Port No. Pries 


"6507 


. . . 6.95 


•6526CIA, . . . 


..14.95 


82S1O0PLA. 19.95 


"6510CPU . . 


. . . 9.95 


■6529SP! 
"65S0V1C-I. . . 


. . . 7.95 
. . 14.96 


"8701 Cteck Clilo ■ . . 9.95 


•65Z5TPI. . . . 


. . . 9.95 


•6S67VIC-H. . 


..19.95 


■8721 PtA 14.95 


Seta. Mbbta • SI . 50 u 


■6581 SID. . . . 


. . 19.95 


NOTE; 826100 = U1T (C^4) 



NEC V2Q & V3Q CHIPS 

Replace the 8086 or 8088 in Your IBM-PC and 
p. rt no Increase Its Speed by up to 40%! p^ 

UPD70108D-5 (5MHz) V20 Chip S11.95 

UPD70108D-8 (8MHi) V20 Chip S16.95 

UPD701 16D-8 (8MHi) V30 CWp S1S.9S 

COMPONENTS 



MICROPROCESSOR CHIPS 

Pari No. Price 



D76&AC 495 

C0P18O2CE 6.95 
2661-3. 6.95 

zao. zeofl. zsob, series 






:■ ■ :.■■■[- 1 


4.95 






Z30A-CTC- - - - 
Z8QA-DART. . . 


1.89 
5.25 


ZftOA-SlO/G Sl25 

Z60B. ............ 3.95 

ZfiOe-CTC 4.95 

ZSOB-FTO 4.05 

B500/eiOO/6SOPO StH. 


65CCC 


1095 














6SOO 


1.95 










6640. 


. . . 6.75 



050D/«8[K1/Oe000 Cant. 
Pirt NO. Pficb 







6645, 












eeoorXA 


9.95 


B00O SERIES 


60CG18H 

3035 

B073N 


19.95 

... 1 .95 
29-95 


B085A. 


2.75 


SOB6-2, 

BOS7(5MHz) 

."■SMH;1 


10l95 

1 29.95 
159.95 


8088-2. 


955 


6155. 


. 2 75 


6155-2 

8156, 


. . . 3.95 
.2,75 






821 2 


1.95 


8228 


. . . 3.49 



SO00 SERIES Conl. 
P>rt No. Prio 

8237-5 6S5 

6243. 2.49 

S250A 695 

sstOB rroi- iqv) . . / 2s 

8251A 225 

8253-5. 2.25 

8254. 9.95 

B254-2 1 1-95 

8255A-5, 2.25 

6257-5. 2.49 

8253-5. 2.49 

6272 4.95 

B279-5. 2.95 

8741 8.95 

6748. 7.95 

S749 9.95 

8751 29.95 

8755. 1435 

DAT* ACQUISITION 
ADCOS04. 3.49 

Aocosaa. 8.95 

AOC0809. 3.95 

AOOD616. 14.95 

APCQ817. 6.95 

C«X)808. 1.95 

DAC1O0B. 7.95 

AY-3-1015D, 4,95 

AV-5-1013A. 395 



Pin No. 



Function 



-DIKMUCMMt- 



4116M-15 

4128 (Piggyback} 

4164N-150 

4184N-200 

TMS4416-12 

MM5280 

8118 

41255-150 

50464-15 



1D.2B.: a 1 
131,072 X 1 
65.536 X 1 
65.636 X 1 
16364x4 
4096x1 
16364 «1 
262,144x1 
65,536x4 



(1 50ns) 

(200TB) 

(150ns) 

(200ns) 

(120ns) 

(2O0ns) 2107 

(120ns) (+5V Only Required). 

(150ns) 

(150fis}(4454)(41464) 

STATIC RAMS- 



Prle* 
. .89 

5.95 
, 1-25 
. 1.15 

4.95 
. 1.95 
99 
. 2.95 
.6.49 



TMM2016-12 20+6x6 (120ns). . 

2102 1024x1 (350ns) 

21 02-2L 1024 X 1 (250ns) LP (91 L02) 

2114N 1024x4 (450ns) 

2114N-L 1024x4 (450ns) LP. 

2114N-2 1024x4 (200ns) 

2114M-2L 1024x4 (200ns) LP 

21C14 1024x4 P00ns)(CMOS) 

2149 1024x4 (45rS) 

5101 256x4 (450ns) CMOS 

HM6116P-3 2048xE (150ns)CMOS. 

HM61 16LP-3 2048 X 8 (150ns) LR CMOS 

HM6254P-12 8192x8 (120ns) CMOS- 

HM6264LP-12 8192x8 (120ns) LR CMOS 

HM6264P-15 8192x8 (150ns) CMOS. 

HM6264LP-15 8192x8 ( 1 50ns) LR CMOS .... 

6514 1024x4 (350ns) CMOS (UP0444C). , 

- PflOMS/EPflOMS 



. 1 59 
. S9 
. 1.49 
. .99 
. 1.09 
. 1.05 
1.49 
. .49 
.435 
. 3.95 
. 1.45 
. 1.49 
.4.09 
. 429 
.3.75 
.389 
.4.49 



1702A 
TMS251 6 
TMS2532 
TMS2564 
2706 

2716 

2716-1 

27C16 

2732 

2732A-20 

2732A-25 

2732A-45 

27C32 

2758 

2764-20 

2764-25 

2764A-25 

2764-46 

27C64 

27126-25 

27128A-25 

27258-25 

27C256-25 

27512-25 

66764 

74S387 

74S471 
82S123 



256x8 

2048x8 

4096x8 

8192x8 

1024x8 

2048x8 

2043x8 

2048x8 

2046x8 

4096x8 

4096x8 

4096xa 

4096x8 

4096x8 

1024x8 

8192x8 

6192X8 

61 92 X 8 

8192x6 

6192x8 

16364x6 

16,384x8 

32,768 X 8 

32.768 X 6 

65,536x8 

8192x8 

8192x8 

256x4 

256X8 

32x8 



(Ids).. 

(450ns) 25V 

(450ns) 2SV 

(450ns) 25V. 

(450ns) 

(450ns) 3 voltage. . 

(450ns) 

(350ns) 2SV, 

CMOS 

(450ns) 

(200ns) 21V. v 

(250ns)21V. 

(450ns) 21 V 

CMOS 

(450ns) Single +SV. 

(200ns) 211?. 

(250ns) 21V 

(260ns) 12.5V. 

(450ns) 21V 

CMOS 21V..... 

(250ns) 126K 21V. ..... 

(250n5) 1 25V. 

(250ns) 256K (12.5V) 

(250ns) 256K (CMOS) (12.5V). 

(250ns) 51 2K (12.5V) 

(450ns) 25V. 

(350ns) 25V 

PROM O.C 

PflOM T.S- 

PHOM IS 



. . 5.95 
..4.95 
. . 5.95 
. , 8 95 
. . 3.49 
. . 9.95 
..3.15 
. , 4.95 
..649 
.375 
..3.95 
..349 
. .3.29 
..649 
.,2.95 
. .395 
. . 3.49 
. . 3.25 
..355 
.,4 95 
.325 
.. 435 
. . 5.95 
. . 8.95 
. 24.95 
. 15.95 
. 1635 
.. 1.69 
. . 4.95 
..2.95 



Pan Mo. 



LOW PROFILE [TIN) SCCHTO 

1-9 10-99 100-op 



8 pin LP. 13 

14pinLP. 15 

16 pin LP. 17 

24 ptn LP. .31 

28 pin LP. 39 

40 pin LP. 49 



.12 


.11 


i:i 


11 


.15 


.13 


30 


29 


37 


!M 


4b 


43 



WIRE WRAP SOCKETS I GOLD) LEVEL #3 



Pan No. 



1-9 10-39 lOO-up 



6 Din WW. 55 

14 pin WW. .69 

16 pin WW. .75 

24pinWW. 1.19 

28 pin WW. 139 

40 pin WW 1 79 



.49 .45 

.55 £9 
,69 .65 
1.09 .99 
1.29 1.19 
1.59 



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supply ihe basic aync (urtclitms for erHior color or mor 
chrome 525 llrWBQHz inte rtacrcJ and camera video t&con 
appiiCaliOr>B. COLOR HURST CJiTE 4 3VNC 

ALLOW STABL E COLOR OPERATION 

MM5321 $9.9 

PIQTALKEn™ 

DT1050 — Applkanon»:TMchlng8W>,*pptl^io 
dock*, aulotnctiv*, ivlKwnmij'nIcatiorts, ttngusgttrarvi 

bofn, c tc. The DTI 050 ii a Standard DIGI TALKER kit rnc c-J 
wtlti 137 uparalQ arid usefut words, 2 tones, and 5 dlffen 
ailB'TlOe durations. Thfl wCKda-fiTid tones hsve been assign 
discrete addresses, making it posaitf le to output single wh 
or wwds. concatenated into pjira»s or even sentoncoa. T 
"K3i^e"uu1c!ut KlthuDTI 050 is u highly intelligible male vdi 
TheOT1050conwtoofsSpe«cnPre«»5*rCnJp, MM 541 
(40-pJn) and twD [2) SpMCh ROMs HMSitMSSRI 4 
MM5215*SSR2 (34-pin) along wftti a U*iHr Word Itttan 
naeommondfld S£h#fnitic diagram cm U 
P»rt No. 



DT1050 D4giWI-r~ $24.9 

MM54104 ptoceMOfCnip ■ ■ . $12.9 

DT1 OST-^Expanffs tho DT1050 ^ocabuEary Irom I 
word's lo aver 250 words. : nd udes two (2) RCWs and spa 



DT1057. 



$11.9 



INTERSIL 



Part Wo. 

FHS202D. 

FE0203D. ..... 

7I06CPL. 
7106EV/KI*. 


Pfioc 
12.95 
1Z95 
8,95 
. 46.95 


Pari No, 
7207AEWKit 

721 1 1PL (TTL) 
721 1MB=L (Micro) 

7217UL 

7217AIR. 

7224IPL 

7226AEV/KK. .... 


Pi 
S 
7, 

...a 

10. 


7107EVy«iL 

7207AIPD 


46.95 

. . . 5.95 


10 



74HC Hl-Spgg" CWIOi 



- SOlDERTAtL STAND ARO 1 5 010 S TIN) AND KEAOEfl PIUS SOCKETS ALSO MAIUtBlI - 



74HO00 


35 


74HC1 75. . . . 


74HCOZ 


3S 


74HC221 1 


74HC04 


39 


74HC240 1 


74HC08. 


39 


74HC244. 1 


74HC10. 


39 


74HC245. 1 


74HC14. 


59 


74HC253 


74HC30. 


39 


74HC269. 1 


74HC32 


^16 


74HC273 1 


74HC74. 


.45 


74HC373, 1 


74MC75. 


.69 


74HC374. 1 


74HG76. 


69 


74HC393. 1 


74HCB5. 


1.19 


74HC595 1 


74HC86 


.59 


74HC688. 1 


74HC123. 


1.19 


74HC4040. 1 


74HC125.... 


.99 


74HO4049 


74HC132..... 


.79 


74HC4OS0. 


74HC138. .... 


.79 


74HC4060. 1 


74HC139..... 


79 


74HC4511 1 








74HC163. .... 


.89 


74HC4538. 1 


74HC174 


. .69 


74HC4543 2 


74.4 


74O00. 


29 


74G174. 


74C02. 


29 


74C1 75 


74D04. 


25 


74C221...- 1 


74O08. 


35 


74C240 1 


74C1CI 


39 


74C244. 1 


74C14. 


.49 


74C373 1 


74C32. 


35 


74C374 1 


74C74 


.49 


74C912 7 


74C85 


1.19 


74C915 1 


74C86. 


29 


74C92D. S 


74C89 


395 


74C921 S 


74C90 


89 


740922. ! 


74C1 54 


2.95 


740923 ; 












UN 


EAR 


□S0O26CM... 


1 .69 


Jv1399H 2 


TL074CN 


.79 


TL497ACN. : 


TL0B4CN 


1.09 


NE540H(C540H)....; 


LM307CN. . . . 


45 


NE555U 


LM309K. 


1.25 


XR-L555 , . 


LM311CM... 


.45 


LM5S6M 


LM317T. 


.99 


NE558N 1 


LM318CN. . , . 


1.19 


LM565N. 


LM319N 


1.19 


LM557V. 


LM320K-5. . . . 


135 


UE592N. 


LM32(JT-5. . . . 


59 


LM741CN 


LM323K. 


4.49 


LM747N 


LM324N 


39 


LM1458CM.. 




335 

.49 




LM339N. 


LM1489N 


LM340K-5. . . . 


135 


LM1496N. 


LM340K-12. .. 


135 


LM1B71M ■ 


LM340K-15... 


135 


LW1872N I 




.49 
j49 




LM340T-12. . 


ULN20Q3A. 


LM340T-15. . . 


.49 


XR220S. ! 


LF347N, 


39 


XH2207. I 


LM34SN 


£9 


>ffi2211 : 


LF351M 


49 


LM2907N. " 


LF353N 


...... SB 


LM2917N<8e«l). .,.' 


LF355N 


BB 


LM390ON 


LF356M. 


39 


LM3905CM ■ 


LM358N 


.49 


LM3909N 


LM3GONL 


2.19 


LM3914h4... ,' 


LM361 M . . . . 


159 


LM391 SM 


LM3S0CM. . . . 


1.09 


NE5532. 


UU1386T^3. . . 


39 




LM387N 


99 


75477 


LM393N. 


.45 


76477. ; 



PARTIAL LISTING • OVER 4000 COMPONENTS AND ACCESSORIES IN STOCK! • CALL FOR QUANTITY DISCOUNTS 



CIRCLE 114 ON FREE INFORMATION CARD 



■■■■■■■^IB 



Worldwide • Since 1974 

• QUALITY COMPONENTS • COMPETITIVE PRICING 
• PROMPT DELIVERY 



Mj.il Ord*r Fl*e(ftrf!iet -Wof1dv*ld» 



TTnT? 



ELECTRONICS 



OMMODORE COMPATIBLE 
ACCESSORIES 



/Vow Compatible 
With C-128! 




RS232 Adapter 
forVIC-20, C-64 
and C-128 



I JE232CM jUowi connection dt standard serial RS232 
nlfrs, modern*, etc to your WC-2C. C-64 (excluding me 
-64 Reliable). and C-12S. A a-pOde switch allow* Hie irh 
vion of the 4 control lion. Complete installation and 
■ration intiruCtodfit Included. 

UQiinto UwrFcwl ♦ Prawtes S lands rd HS23? HgnaJ leveiS 
ses 6 si q n,Tti s ! Tr an inni-L Receive, Cleat to Send. Request lo 
id. Data Terminal Heady Dala Set Ready). 

E232CM $39.95 

Voice Synthesizer VIC-20 & C-64 

Plug-In — Talking in Minutes! 

E520CM , . . . $99.95 

300 Baud Auto Modem 
itey-Mo ifotc-m) S54.95 

Parallel Printer Interface 

2K Sutler. Expandable to 10KI 

W350 (Forvic-ao.c-S4ic.i2si $54.95 

TRS-80* COMPATIBLE 
ACCESSORIES 

E-X-P-A-N-D TRS-80 MEMORY 

All kits come complete with documentation 



TRS-80 MODEL I, III 

IS-16K3 300ns (Model III) $5.95 

IS-16K4 250ns [Model I) $5.49 

TRS-80 COLOR AND COLOR II 

1S-64K-2 S11.95 

New models only — 
tS-CoCo-lncl. 2 -50464 s <414S4'a) 513.49 

TRS-80 MODEL 4, 4P 

)S-E4K-2. S11.95 

psnds Model* horn 1 SK-64KM Mooal 4Plrom 64K-1I8K 
1S-64K-2WU- S29.9S 

panda Modal 4 Itom 64K Id I3SS 

RS-80 Model 100 • NEC • Olivetti 

1008K. $29.95 ea. or 3 for S79.95 

:S-BQ Model too Expansion 

EC8KR S29.95 ea. or 3 for S79.9S 

:C Modal PC -3201 A Ejroanaion 

M10SK. $29.95 ea. or 3 for $79.95 

ivettl Modal M10 Expansion 

TANDY 200 

200R $74.95 ea, or Z tor S1Z9.95 

ndy Model 300 Expansion 

UV-EPHOM ERASER 

■A 



i»i all E PHOMs. Erai a* up to 3 cN pi wrthl n 2 1 mm Lite* 
chip in 1 5 minuletk Ma intain s ccmsia.nl exposure d isla ice 
1 '. Special conductive team liner mm males static build-up. 
jilt-irt safety Jock Ho prevent UV exposure. Co™ pad - 3 D-U'L 
X7<m x 2,6Q» Comptele wiTh holding tray tpr 8 chips 

lE-4 UV-EPHOM Eraser. . - . $74.95 

IVS-1 1 EL Replacement Bulb, . . , $17,95 



DATA BOOKS 



0003 National Linear Data Book (32) $1 4.95 

0009 Intern I Data Booh IBS) $ 9.95 

0013 Ziloa Det* Book (fl5) S14.95 

0022 Natl Logic Data Book Set (M). $24.95 

10830 Intel Memory Handbook ftt) S17.95 

30S43 >mn Mtoojaj*«n Hndbfc, Set (66) $24.95 

IUFF1H/3PRTE-STY1.E WHS 



M UF6Q (SPN3- 1 5-2<62J .... S9.9 5 
Howard Industrie* (4.63" sg, . 60 dm I 

SU2C7 S9.95 

EGAG Rolron (3, 125' square, 20 elm) 





13" Color 
Composite Monitor 

for VIC-20 and C-64 
Also compatible with other 
computers with composite 
output (i.e. Apple II, ll+, lie') 
Ideal lor color graphics and games 

■ Resolution 1 260H X SttfW-fleeom mended 
Display Character Number 960 Characters 
t40 Character s x 24 Hows on 5 x 7 Dot Matrix) 

■ CRT: 1 3" diagonal - Sire : 1 4.6^ x 1 3 5'H 
X15.5T). Weight 25 3 lbs _ . 

2 for 
CMON.7VT. . . . $129.95 each or $219.95 

RCA-3-DIN (UnrwfHl Compute* to Monitor Cables for Atari, Commodore ATT), . , . 53,49 



ZUCKISRIJO'AMO 




or 640K. The memory board 



Expansion Memory 
Half Card and 

Clock/Calendar for 
the Tandy 1000 

The Zuckerboard Expansion Memory Board 

allows you to expand the memory oi your 
Tandy 1000 (128K Model) as much as 640K! 
256K DRAM chips increase your computer's 
memory by eilher 256K or 5T2K, bringing 
your total system memory up to eilher 3S4K 
Iso includes a DMA controller chip. Optional 



clock/eaten da r plugs directly onto the memory board. Manual included. 
TAN -Clock Clock/Calendar Option (only). $ 39.95 

TAN-EM256K includes 25SK ram S 99.95 

TAN-EM512K includes 512K bam $139.95 



■!■ ■■■■■ 
BIG BOARD 



1 MBYTE RAM CARD 
for Apple II, II+ and lie' 




Introducing a Ihird generation memory card that gives you both great expand- 
ability and great versatility at an extraordinary price. Versatility to users means 
that BIG BOARD is compatible with software written for the Synetix SSD 
(Flashcard) as well as for Jameco's JE868 128K RAM Card Big Board makes 
available 426K ol worksheet space, using the program THE Spreadsheet 
Version 2.0 II is compatible wilh PLUSWORKS XM lor running Appleworks 
on Ihe Apple II. Versatility also means that BIG BOARD comes complete with 
RAMOISK software tor DOS 3.3. ProDOS, Rascal 1 .2. and CP/M lor Microsoft's 
Softcard. A separate driver is available for the AppliCarrj iStarCard). 

BIG BOARD-256K 256K RAM. $199.95 

BIG BOARD-512K 51 2K RAM $249.95 



BIGBOARD-1M IMegRAM. 



$299.95 



1 Yr. Warranty! 




External Power Supply 
for the Commodore 64 

■ Input: 117VAC 6 6OH1 • Output: 5VDC « 
3 Am ps. 1 0VAC e 250m A ■ Short circu it pro- 
tected and current limited - Transient spike 
suppression on 2 auxiliary M0VAC sockets 
* Switch on front serves as power switch 
lor the computer and other peripherals 
- RFI/EMI filtered ■ Adjustable linear regu- 
lator - Has less than 50mV ripple rms at full 
load - 5 Amp primary fuse ■ Two conductor 
with ground line - Color; brown ■ Size: 7Vj"D 
x SVW x 2^~H • Weight: 5 lbs 

CPS-10 $39.95 



IBM* COMPATIBLE 
ACCESSORIES 

83-KEY KEYBOARD 



» MyuauMyagnriM 'LjiLL. 



- Identical layout as original IBM PC Keyboard - Highly 
desirable case with palm rest - Complete wilh cable anddala 

■ just nun mi 

KBS3....... $39.95 

Build an IBM PCI XV Compatible! 

IBM-64K(2) mk ram Chips (is) $ 24.98 

KB-83 M-Key Keyboard $ 39.95 

IBM-FCC Bon* ComrotH card S 49.95 

IBM-Case 0. $ 49.95 

IBM-MCC Monoctiroma Card S 69.35 

IBM-PS Bowwsuppiy $ 89.95 

FDS58 DiskDriv. $119.95 

IBM- MOM Monochrome Mentor. . . . 5109.95 

IBM-MB Motharboard . $169.95 

Regular List $744,58 
IBM "-Special gKtiggMgwg . . S649.95 
Additional Add-Ons Available! 



IBM-KB 
IBM-EN H 
IBM-ICB 
IBM-EGA 



(J-Key Keyboard 

Enhanced Keyboerd. . . . 
Integrated Color Board . . 
ErtM CapmnSSSKIUM 



1BM-20MBK 2TJMB Hard P»k Phve. 



S 79.95 

S 99.95 

. S1 09.95 

.$349.95 

. S499.95 



rtWu a registered Jrjdemar* ol IBU Computers 

..«-iifl Universal «#<*■. 

NEW ! 64K/256K / *^H7 



s 



Printer Buffer 

I^HNATHOK FRE£.MAN Df5[CK? 



The UBUFFER Uninver-ia I Printer Buffer is a hl-speed data 
CNjHer lhat accepts dala al a high rale, and Ihen outputs mis 

data to your printer. Ypu save valuable -compurer time The 
UBUFFER con be connected lo practically any compolbW or 
primer. There are Four possible camhi nations- 1> Serial to 
Serial, 2) Serial To Parallel, 3 r Parallel lo Parallel. Ai Parallel 
lo Serial. Manual Included. Size- 3-1/31- x 4'h"W x 1 VH 



UBUFFER-64K . 
UBUFFER-256K 



$199.95 
$229.95 




IBM 
* / Compatible! 
DISK DRIVES 

Dr-Cu'm e n rjnon 
ranrJOtd 

FD55B Te K 51*" PS 'VHehgh S1 19.95 

SA455 Shugart SV DS Vi-Hefght $119.95 

TM100-2 Tandon sv.- DS Full-Helghl. , . . $139.95 

JMR 5V4 1 DISK DRIVE ENCLOSURES 

CompJet* wrih powTH- supply, switch.. 
power cord. Fuieholder and connectori, 

DDE-1FH S69.95 

HOuies 1 Full-Heighl 5 1 *" Floppy Drive 

DDE-2HH $79.95 

Houses 2 Halt-Height sv Floppy bnves - Vertical 

HDDE-1FH $199.95 

Houses 1 Hard Disk Drive 



$20 Minimum Order - U.S. Funds Only 

Shipping: Add 5% plus $1 .50 Insurance 



California Residents: Add 6% or 6 Wa Sales Tax 

CIRCLE 114 ON FREE INFORMATION CARD 



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self-addressed envelope 

to receive a Quarterly 

Sales Flyer - FREE! 

9/86 




ECS 



I® 



amGco 



ELECTRONICS 



VISA' 



Spec. Sheets - 30c each 
Prices Subject to Change 

Send $1,00 Postage for a 

FREE 

1986JAMECO 

CATALOG 

* 1986 Jameco Electronics 



1355 SHOREWAY ROAD, BELMONT, CA 94002 • PHONE ORDERS WELCOME 415-592-8097 Telex: 176043 



CIRCLE 114 ON FREE INFORMATION CARD 



MARK V ELECTRONICS INC. 

248 EAST MAIN STREET. SUITE 100, 
ALHAMBRA. CA91801. 
TELEX: 3716914 MARK 5. 



TOLL FREE FOR ORDERS PAID BY MASTER OR VISA CARD 

PLEASE CALL: 1-800-423-3483 

IN CALIFORNIA: 1-800-521-MARK 

INFORMATION; 1-818-282-1196 

MAIL ORDERS: P.O. BOX 7065 ALHAMBRA CA 91802. 



Masi«fCofd, 




CALL OR WRITE FOR A FREE CATALOG — OVER 60 HOT & WELL-QUALIFIED tTEMS FOR YOUR SELECTION! 



TR-100 0-15V 2A REGULATED DC POWER SUW.Y 




80W + 80W DC LOW TIM 
PRE-MAIN AMPLIFIER rtM 



* Output vollage is adjustabJe from Q 15V DC two tui/em 
limit range are available forselection; 200mA or 2A. 

* An elaborated prelection syatom Is specially designed, a 
'BB' sound and a sparkle light will appear when the output it 
■ ;. ■-• a ■ ■ i . ■■■ i •:■ J or ■ i ■■■:■; 

■ High stability and reliable resulting from Employing nigh 
quality voltage regulate IC. 

* Possessing king -sue meter makes ghe reading of voltage and 
current more clearly and accuracy. 

A refined data, meter and all accessory are enclosed for both 
kit and assembly form. Most suitable for factory, profn* 
tional or even amateur. 

Kit $59.50 

An. with tester* - . 1 _ - -_, ^ ^ . . ^ ■ . : ■ ■ ■ . . . . *6a.W 

"cordless solderingTroKT 

RECHARGEABLE ^ jj^h. 




The mosi perfect handy, lightweight soldering iron lor Work' 
ihop„ hanw, Hobby & Outdoor work . - , 

Includes UL approval charger & cleaning sponge, 

With build-In solder point illumination. 

Each set 5*2 e° 




1. TMh punh buiiort. tor vtuce »nnuuriMrrt*nt oUrm* 

2- Hatd nul: Iwelvp hours fyslcm chioljv far h»ur. minulc s«Qnrj Iby colon 

|j«h : . AM & PM. 
3 Dupl *y- ihra* dnplAy mods* n1 nmt. Hum hmo A dure 
*,. Alarrft: on g]T switch wi]h thirtf icccmdi voice aljrm 
5 S«OOie: reminder voi CO jl«rmol thirty weQnd&irtflr<l minuAmjl drm1 none 

sflarm 

6. V^Lmc two level at ^n k r/vitpuL 

7. Langujg* iwallBhle: Englhih. Mandarin. 

M T nih8504 J2S.M NDTAKITI 

3% DIGITAL MULTIMETER 



YAMATO 



The VAMATO 4001 is a 3^ DIGIT COMPACT DIGITAL 
MULtlMETER, It employs FE type LCD. with large figures. Its 

ADVANTAGES: High accuracy in measuring, High impedance 
assures mm measuring error. One rotary switch allows fast & 
convenient operation. 26 measurement range enable wider 
application. Over-input indication & low battery life appears on 
display. LSI-circuit use provides high reliability and durability. 
Measurement possible even under strong magnetic field. 
Net e KIT. assembled with tested $33-80 





Kit ^ T /*/*:> . £49.85 

Metal CiMnetSX'Formar [Optional} tto.$Qt$22M 



TA-1500 100W + 100W NEW CLASS 'A' DC 
STEREO PRE-MAIN AMPLIFIER 



COLOR LIGHT CONTROLLER 

TY-23B 





Feature*; 

1. Preamp employs three LOW NOISE OpAmp. as ftLAA 
equalLitr and 2MB Hal amplifier and lone control. It has very 
good transient response and low none It is easy to build up. 

2. Power Amp. employs out powerful audio transistors end 
an advanced dynamic bass class 'A' circuit. The dissipation is 
extremely low and this makes the output stage at minimal 
switching distortion. Ii can reproduce high level boss 
fBithMly- 

3. A specially designed delay System is included and lh« 
functions contains: Lei three seconds delay, lb| output short 
circuit protection, fci DC output protection. It also equipped 
with LED indicator of double display. 

4. It include* a microphone mixer, so you can sing with 
thos« famous singers together, ii can also ba used as a Public 
Address Amplifier. 

Kit M7.00 

Metal Cabinet/XrC-rmer (Optional] . . $23.90/$22M 

H-O-*"*-*-*-*-*-* 



10W AC/DC 
SHOULDER AMPLIFIER 



As a raaull Of Ibe advanced technology, this unit can control 
various colorful tight bulbs, the visual effect of which is mosi 
suitable in places like party, disco, electronic g a m« centre and 
also in lightings for advertisement. Total output power is 
3000W IIQOOW/Ch.l which means that it can control 30 pieces 
of 100W or 600 pieces of 5W color light which is enough for 
most usages. 

Kit S65.(K> 

Asi. with tested $75.1)0 

TA-2400A ELECTRONIC ECHO AND 
REVERBERATION AMPLIFIER 

s REMIX records yoursalf! i 



This unil combines fhe most advanced V.L.S-1- technique 

with high quality Japan mad* components. It has the 

1 oil owing FEATURES: 

li can generate various reflection and reverberation affects as 

ihos* occunrig in valleys and music halls. It has 3 special 

elfatf controls which include reverberation control, delay 

control and depth control, Special effect can be made in your 

record tapes by suing this model. All kinds of Infield sound 

effect can be obtelned by skilful use of this control. It has LED 

display to show rellect ion and reverberation. 

Ass. with tasted (99,85 




TA-OOfl 



Ta 008 employs the most advanced t.C. of TOSHIBA, as a 
main device. th« sound is powerful, it can be supplied by Only 
4 pieces of 'UM-V 1 ,5V battery or AC to DC 6-9V adaptor. It is 
simplsto operate, just 'press-to-taUt'. and with ON -OFF power 
switch on the mike. Besides, while it is well-packaged and 
with light weight, so it is convenient to bring along m both 
indoor and Outdoor activities- Please Read our catalog lor 
details. 
Assembled with tested t*B.OO 

STir^^rlUllATOrr 




^SPECIALS- 

KITS 
i OFFER \\ 



TA-3000 



KIT ONLY $25 00 {Case included) 

Vi'in can own a stereo TV from today 1 This simulator is a 
special design of using the most advanceable monoploised 
L.S.I, It produced a superior analog stereo effect line* the 
L8.L Is equalled 60 pes. of LOW NOISE FET 4 TRANSISTOR. 
The simulator can even help you to promote your television 
From a normal one Co a special one with a Hi-F= STEREO Junc- 
tion. Our simulator is also applicable to any other 'mono 
sources' tn covering it to ANALOG STEREO. Undoubtedly, it is 
the most advanced equipment for every family, while it 
should contribute to your listening pleasure, 

130.00 



*-o - * O -i 



HIGH QUALITY 
MULTIPURPOSE PRE AMPLIFIER 



This Specially designed pre-ampliiier includes a professional 
GRAPHIC EQUALIZER TONE control system and has a gain of 
■ 12dR. Frequency response extends Irom 5 Hz to 20KH;. so 
as to ensure best performance in whatever adverse condi- 
tion. It can accept input from various magnetic cartridge, 
record : l !'!■■.". , CD player and tuner: its output can be con- 
nected to all kinds ol power amplifier! 
Assembled with tested „„ S32 00 

120WMOSFET POWER AMPLIFIER 



This amplifier consists Of three super low TIM differential 
stages, and Hitachi 2SJ4&2SK 134 match pair TMQSfET* as 

oulpul component whose frequency response and transient 
response is superior to the other power transistor. Therefore 
this ampUlier has high-fidelity and superior Analytic power 
over the entire Audio Spectrum. It is suitable-fox reproducing 
ctassic and modarn music, Heavy Duty Heat Sink iwith 28 
radial fins is included 1 

Kit , , *5S,W 

Metal CaUMt/X'Formar (Optional] S23 90/il 3.S8 

■^S^g-fr-^T-O-— lHB^#-a-* i ■ Q ■ ■ Q 1 ■ ■ ■ fr^^-fr-T^»-<M^*-C"»H 



Model ISo. 

TA-001 

TA-IXN3 
TA-H»7 

TA-OXM 

TA-IO 

TA^SO A, B 

TA-12P 

TA-202 

TA-3O0 

TA-302 

TA-323A 

TA-3Z2. 

TA-400 

TA-477 

TA-8W 

TA-602 

TA-820A 

TA-10O0A 

TA-tSOO 

TA-2400A 

TA-2600 

TA-220O 

TA-2BDO 

TA^arjoo 



SM-1DO 
TY-43 



KuyAitemtiJcd Unn Poet 



tW Mfnl Amplilier 

6W Mini Amplifier 

1 2W Strreo Power BoOitar 

ACmC SHOULDER AMPLIFIER 

STEREO PRE AMPLIFIER WITH MAGNETIC MIC AMP 

MULTI PURPOSE MELODY OE^ERaTOR 

PURE CLASS "A" MAIN POWER AMPLIFIER 

20W AC/DC STEREO AMPLIFI ER 

SOW MutnPurpoji Single Channel Amp. 

60W sin en Power Buu-.if • 

High Ouahty 30W^30Vg Stereo Amplifier 

COW IC Stereo Pre^Amplifiar & Power Amphhtr 

4QW TRANSISTORIZED MONO-AMPLIFIER 

130WMOSFET POWER AMPLIFIER 

} SOW DC LOW T I M f>RE AM PL I F IE R & POWE R AMP. 

160W PURE DC ST POWER AMP W SPK. PROTECTOR 

120W OCL DC PHE-MAIN & STEREO AMPLIFIER 

tD0W DYNAMIC CLASS "A" MAIN POWER AMP iMOtvOi 

200W NEW CLASS "A" DC STEREO PRE MAIN AMP 

ELECTRONIC ECHO AND REVERBERATION AMP 

HIGH QUALITY MULTI-PURPOSE PREAMPLIFIER 

DC FET SUPER CLASS "A" PREAMPLIFIER 

NF-CR BI-FET PRE-AMP (WITH 3WAY TONE CONTROL! 

STEREO SIMULATOR 

3 \& MULTI FUNCTIONAL LED OP.M. 

* If* Ml PRECISION DP.M. 

1S0MC UNlVEftSAL DIGITAL FREQUENCY COUNTER 
J W2 DIGITAL PANEL METER 



KlE 

Kn 


33.30 

mo: 


Kit 


S8f» 


Ass 


S-UI'JO 


Kit 


Sf. mi 


Kn 


310.76 


Kit 


S25.00 


Ass 


S60.W 


Kit 


St 1 07 


Kit 


SS0Q0 


Au 


SfiOOP 


Kit 


$24.60 


Kil 


SVD tO 


Kit 


STiE4 


Kit 


S55.00 


Kit 


&49.B5 


KLI 


S39S5 


Kil 


£43.00 


Kn 


Sit. 6li 


Krt 


567,00 


Am 


S93.36 


Ah 


562.00 


KH 


$3a.oo 


Kit 


S3EB0 


Ah 


S30 00 


KL,r 


$2S.O0 


Kit 


$29 23 


Ass 


33S.00 


Kn 


S13« 


An 


$43fXI 


An 


599 00 


KM 


£28.00 



Model No 
TR-35S A, & 
TR-5G3 



TH-1O0 

TY-tAMK4 

TY-7 

TY-tlA 

TY-12A 

TY-13 

TV-14 

TV— IB 

TY-2Q 

TY-239 

TV^25 
TY-35 

TY-36 
TY-3B 
TY-41 MKIII 

TY-42 

TY-45 

TY-47 

VAMAT0 4001 

Tl 

T2 

B504 

NO. 620 



Ass-Antmbltd forr 



Description 

35A REGULATED DC POWER SUPPLY 

0-50V 3A POWER SUPPLY WITH SHORT CIRCUIT BREAK 

A OVERLOAD PBOTECTOH 

0-15V2A REGULATED DC POWER SUPPLY 

BATTERY FLUOPESCENT LIGHT 
ELECTRONIC TOUCH SWITCH 
MULTI-FUNCTIONAL CONTROL RELAV 
DIGITAL CLOCK WITH TWO TIMER 
COLOR LEO VU METER 
ELECTRONIC SHOCK 

HIGH PRECISION SOUND CONTROL SWITCH 
SUPER SENSITIVE AUDIO LEVEL INDICATOR 
COLOR LIGHT CONTROLLER 

SPEAKER PROTECTOR 
PM WIRELESS MICROPHONE 
ACxOC QUARTZ DIGITAL CLOCK 
SOUND OR TOUCH CONTROL SWITCH 
INFRARED REMOTE CONTROL UNIT 

BAR/DDT LEVEL METER 

BAR/DOT AUDIO LEVEL DISPLAY 

SUPERIOR ELECTRONIC ROULETTE 

3M DIGITAL MULTIMETER 

tCD tmLfltfOMLTER CLOCK WflN A Out DOGn S^hSOH 

LCP THERMOMtnH CLOCK WrT* £. C* MEA5Llfl"M& 

TALKING CLOCK MYNAH [GOLDEN OR BLACK) 

CORDLESS SOLDERING IRON RECHARGEABLE 



Kir/Avtemtriee 



Ah 
K.i 



An 
Kit 
Kit 
Kit 

6>SET 
*>SET 

• SET 
PSET 

• SET 



Urnt Price 
$10.63 

£12.30 

$63.50 

S».W 

$3 90 

$S.SO 

$3 99 

SH2h 

51?,50 

$3.00 

$7.B8 

$19.50 

$6500 

S7500 

$3 50 

$7.6fi 

&16-92 

SlOQO 

£25.00 

$30.00 

$21.00 

$34.95 

$1S.A2 

333-30 

S20.00 

$1B.00 

$25.00 

£22 60 



l fully (■ necked and ies1*0. 



TERMS; Minimum order: $10.00. Charge card order $20 h 00. No C.O.DJ Check & Money order, phone order accept, CA. residents must in- 
clude 6.5% sales tsx T Prices sr subject to change without notice. All merchandise subject to prior sale. Shipping & handling: Inside L.A. 5% of 
total order (Min. $1.50). Outside L.A. 10% of total orde (Min. $2.50), Outside U.S.A. 20% of total order (Min. $5.00). Shipped by UPS ground. 
HOURS: Mon-Fri 9:30 to 5:00 P Sat 9:30 to 1 :QQ (PACIFIC TIME) 
NATION-vVtDE DISTRIBUTORS WANTED FOR OUR PRODUCTS, QUANTITY DISCOUNTS AVAILABLE! 



102 



CIRCLE 93 ON FREE INFORMATION CARD 



*0*l2%#** PW f F ASTS^ P ^ 



€S*. 



f5& 



*&*. 



&\ 



fcfc^*^ SLIM LINE 

■•^ rnni inci ca m 



EDGE 
CONNECTORS 

ALLARE1.S6 SPACING. 

tab-**--' '—*W3 

T wiitmHtiimitinuiHiHH — 
II EDGE CONNECTOR 11.25 ti 
soldorlug style ,o tor $11 .00 

22/44 EDSE CONNECTOR 
$2O0ea PC.atyta 10 lor 111.00 

32/44 EDGE CONNECTOR 
solder lug style $2.50 each 

2>/SS EDSE CONNECTOR 

$2.50 aa PC. stylo 10 lot J 22.00 

31/72 EDGE CONNECTOR 

RC. style *J.M«Ch 

49/11 EDGE CONNECTOR 

PC style $4.90 each 

TRANSISTORS 



i tiros 

2N2222A 
PN2222A 

2N2304 
2N2904 
IN2S05 
MJ215S 
2N3055 
PMD 10X40 
TIP 121 
TIP 125 



4 lot (1.00 

3 lot (1.00 

4 lor tl.00 
3 lot 11.00 
J lor $1.00 
3 lor J1 .00 

St 50 

$1.00 

$1.00 

7S* 

75* 



TRANSFORMERS 



120 volt 
primaries 



\k 



S.S MM OT»i«. 13 M 

(vetti^ 1»mi, S1.2S 

S J Mil OtOOnu. S3. CO 

13 V.CT ■" h 200 mi. 52 oa 

U V£T, Q 400 nu. *3 00 

1Z V.CT. ft 1 amp 14.00 

« V.CT ft 2 «np «.W 

12V-CT. *3 4*mp ST.M 

1» will O (SO m*. «30 

at V.C.T. o zoo ™. is jo 

34 MX ft 1 imp t44& 

24 V-CX : 2 amp S6-75 

34 V.CT. O 3 imp )^S0 

34 VCX ,-■ A imp 1H.D0 

» VtCT. O 135 mi- 13.00 

WALL 
TRANSFORMERS 




4 VDC tt 70 me. 
(VACtfSOOma. 
B VDC ft 750 ma. 

SVDCttSOOma. 

luwtnti* 

14 VAC 4r 11 VA and 
4.5 VAC 1.21 VA $3.50 

24 VAC ©250 ma. s3 00 

MULTI-YOLTAOE O 500 mr. 
3,4 "i , 5.7 V>,« or 1 2 VDC 17 50 




Heavy-duty piacK 
phenoec project box wnb cover and 
•ctl«l.2H'X1WX1V.r 

FUSES D D 

3 AG (AGO SIZE 

I. Hi, 2. 2V..3.4. 5. 6 AMP 

Gm» SIZE aff=^» 

1.2. 3.4. SAMP Mc: "" 
5 df arty ONE amperate 75< 



SOUND 
AND VIDEO MODULATOR 
FOR T.I. COMPUTER 

T I * U M 1 38 1 ■ 1 Desigrvsd for us* with T.I com ■ 

outers. Can be used Willi vnoeo sources. Qulll-rti 
A/B switch. Channel 3 or 4 selection switch . 
Operate otil 2 vdc Hook -up diagram included. 

CAT* AVMOD WERES10.00 REDUCED TO S5.00 EACH 



SPfCMIS 

1 AMP 50 VOLT DIODES 

IN4001 TAPE AND HEEL 
100 lot (4.50 

1000 for $30.00 

SOLDER TAIL I.C. 
SOCKETS 

24 PIN 10 lor 12.50 

100 for $22. 00 

1000 lot 5200.00 



• SPECIAL PRICE* 
TRANSISTOR 

plastic transistor 
PN3569 TO-92 N.P.N. 

100 let S8.00 
1000 tor (60.00 
LARGE QUANTITIES 

AVAILABLE 



48 KEY ASSEMBLY 
FOR COMPUTER OR 
HOBBYIST 




NEWT.I. KEYBOARDS. Otigriaty 
used on com outers, these key- 
boards contain 48 S.P.S.T.mecn- 
anical Switches. Terminates lo 
15 pin connector. Frame 4" x 9" 
CAT*KP-)B $6.50 each 
2 for $.1 1.00 



COOLING FAN 





E[rit*S9XMie2toiv 
noise fart Measures 
3V Equate I r deep 
21 elm, 23 do, 1700 rpm. 

SPECIAL PR let .,.(12.50 each 



MICRO-CASSETTE MECHANISM 

Micro-cassette tape transport for 
standard MC60 01 MC45 

micro- cassettes. 3 Vdc operation. 
Contains: drive motor, belt, head, 
capstan, pinch wheel and otner 
componanls. 3 1/2" X 2 1/4" X 5/8" 
CAT* MCMEC *3,00 each 10forS27.Sa 




COMPUTER O 

GRADE 
CAPACITORS I 

2,000 mid, 200 Vdo t_U 
13«rx Thigh $2,00 

6.400 mrd. (0 Vdc 
1 3/8" X 3 3/4* high $2.50 
0,700 mid. 50 Vdc 
1 3/S- > 4 1/2* high $3.00 
31,000 mid. 15 Vdc 
13M-i4"liigh $2,50 

50,000 mid. 40 Vdc 
3"):S3/4-h!Qll $4.50 

50,000 mid. 40 Vdc 
CfiS-hijh (3.50 

66,000 mid. 15 Vdc 
3 - 1 3 3/4" Noh $3.00 

66,000 mtd. 30 Vdc 
3" x 5 1/4" high $3.50 

5,500 mtd. 30 Vdc 

I 3/8- 1 3 1/2- high $1.00 

5,000 mid. 30 Vdc 

1 3/8" x 2 1/4- high $1 00 

9,300 mid. 50 Vdc 

2- x 4 1/2- high $1.00 

16,000 mid. 10 Vdc 

1 m m x 2 s/8" high $1.00 
40,000 mfd. 10 Vdc 

2 112-13 1/4" high (1,00 
100.000 mid. 10 Vdc 

2 112" «. 6* Ugh (1.00 

185,000 mid. 5 Vdc 
2 If? » 4 jg* high (1 .00 



Tl SWITCHING POWER SUPPLY 

Compact, woU-refluUled Switching power supply 

designed to powor Taxes Inslrurmnls computet 

llWf " 14 - 25 vac f» 1 amp* SPECIAL 

OUTPUT +12 vO5(B350tua. PRICE' 

+ 5vdcSl.2omp „ „ 

-5vdc@200ma. *"*' 

SIZE: 44i* x 4H- x 1 «- high each 




13.8 VDC REGULATED POWER SUPPLY 

Thflss are solid stale. Mtyfegijlflt«J 13.S vdc 
power aupplws. Sosh twin 100% solid state- 
COnstr-jcTlChfl, fuse prarcctiun. and L F D pow«r 
ind [sunn I. J L I. :=. I n ■■? 

2 imp ceniiijanl, 4 imp turga J20,W *ich 

3»rrl[>Conitani. SampiurgH J27.50 «pch 




D.C. CONVERTER 




D e stnned to provide a steady ^ 5 
vdc @ 240 ma. Irom a hattery 
supply ol 3 5 to 6. 25 volts . 
i'/il'Ht'/.iH'"/!!' 

$1.50 each 



TWIST-LOCK 
CONNECTOR 



c^M 



Soma as Switchers!! #12CL5H. 
5 conductor in-Erta plug and chassis 
mount |«cx . Twi sr-loc k style. 
S!.50fSET 



RELAYS 

10 AMP SOLID STATE 

CONTROL; 3 -32 vdc fp^\ 
LOAD: 140 vac 10 imp k>.-/~r*t\ 
SIZE: 2VJ- 1 *-x »" 'T'>5lJ 

$9.50 EACH 10 FOR $90.00 

ULTRA-MINIATURE 

5 VDC RELAY 

Fujittu # 

FBH211NED005M20 
HWiaonartlvlly 
COIL 120 ohms 
CONTACTS: lamp 
Mounts In 1 4 pin DIP socket 
t1 .25 each 10 lor $10.00 

MINIATURE 

6 VDC RELAY 
Aromat#RSO-0V 
Super Smalt 
S.PD T relay 
QOw coram 
contacts rated 

1 amp @ 30 vdc. Highly sensitive 
TTL dinict ddvo possible. 120 ohm 
col. 

Operate Irom 4.3 - 6 vdC. 
COIL: 120 ohms 11,50 ..eh 
1 '!„ > "/n" « '/,,' 1 for 1 13 .50 

13 VDC RELAY 

CONTACTS: S.RN.C. 
10smp@120vac 
Energize eoi to 
ooericonlact... 
COIL' 13 vdc 550 ohms 

SPECIAL PfltCE (1 .00 McH 

4PDT RELAY 

14 paiKH stylo... 
3 amp con tail s . 
USED but luHy 
tested . .$1.70 eicn 
apKsTf cos voltage desired 
E.lher24vdcorl20vsc 
LARGE OuAeFTmES AVAILABLE 

SOCKETS FOft KH RELAY 

75c each 



Star *SMB-0GL 

fivdc 

TTL compatible 

$1. DO each 

10 for SO. DO 



± 12 Vdc or 24Vdc POWER SUPPLY 



DELTR0N MODEL QDI2/1 5-1.7 

Dual pi js and minus 12Vdc open 

Itsms powtr sunpiy Can t* useB i^ 

24Vdc @ 1 .5 amp. INPUT: tidier 

115 Vac or 230 var 

Fully rerfljlaies computer erade supnhi 

7-x4Vx2V 



112.50 each 10 for $110.00 




PHOTO-FLASH 
CAPACITORS 



70 ml 330V 
75' aa. 

CAT* PPC-170 

400 nl 330v 

1.00 U. 
CAT* PPC-400 

600 ml 330V 

1.35 ea. 
CAT* PPC-80rj 




RECHARGEABLE 
NI-CAD BATTERIES 



AAA SIZE 1.25V SOOmAH $1.85 
AA SIZE 1 25V SOOmAH $1.85 
AA with solder (ah $2 00 

C SIZE 1.2V 120Lm«H $3.50 
SUB-C SIZE solder lib $3.50 
DSIZE 12V 1200mA H $3.50 



UNIVERSAL CHARGER 



Will charge 4-AA. CD. or AAA 
m-cads or one 9 volt ni-cad ai 

one time. .. 
(11.00 per charger 



.7 1-JI1AI lTIVjJ 
LOS ANGELES. CA STORE 
905 S Vermont Ave 

213 380 6 000 

VAN NUYS. CA STORE 
S228 Sepulveda Blvd 

818 9971906 



MAtL ORDERS TO 

P.O BOX 20406 

Los Angeles. CA 90006 

TWX - 5101010163 ALL ELECTRONIC 
EASYLINK MUX 62887748 



ASM 




3W SPEAKER 

BohtTi 
imped snoe, 
fit IfX FuHiTflTeg* 

"■■■■ 1 spsak#f. 
T*J flMmagnrBt 
*' flragor-a ' 
f rrwunrtirtg centers 

$2,50 8Bch 10 for (20.00 

SPRING LEVER 
TERMINALS 

TWq color 
coded 

terminal s on a 
iturcty 2- * x 
3**" b«kdit« 
oiale. 

Grtat lor-speaKor tnckisuim or 
cow auppiiM 
75c EACH 10 for $S,00 



tglg 



UNE CORDS 

TWO WIRE 

6 18/2SPT-1IK1 3 lot $1.00 

S'ia/2SPT-2lt«t 21or$1,00 

5 16/2SJT round $1.25 each 
THREE WIRE 

6 18/3 flat (1.50 each 
8 18/3 round $2.00 each 

7 CONDUCTOR 
RIBBON CABLE 

10 




Spaclrs-slrip red marker slnp. 
2agfl.airandedvtira. 

$5.00 pet 100 roll 



XENON FLASH TUBE 



3/4 - longX1iB"dia. Flash 
tube designed lor use in 
compaci camera flasn unils. 
Ideal for experi mentors. 
CAT* FLT-1 2 for $1.00 



MINIATURE TOGGLE SWITCHES 

ALL ARE RATED 5 AMPS Q 125 VAC 




STANDARD JUMRO 
DIFFUSED T 1-3/4 

HEO 10 lor (1.50 *\ 

100 lor tl 3.00 i, 

CPEEN 10 lor 52 00 M 

100 ror $17.00 II 

YELLOW 10 lor $2.00 

. 100for$17.00 |l 

FLASHER LED 

5 vOH Ope r a1 ion 
r*d|urTvboTl ] Hi 
»» si. oo each 
NEW GREEN FLASHEH 
CAT*L£D4G $1.00 

m Dni AD |UinboT1l4 5izfl 
Ol KULAH 2 (or 1170 

LED HOLDERS _ 

Two piflctrnoWer ™ Vm 
fcriutTiboLED ^*^ 

10 'or 55-: iCOi^r ?■= 00 

CLEAR CUPLITE 

LED HOLDER 

Mane LED i f&r-cy <^*"^. 
* tor Si. 00 *?- w 



I 




O.RS,T. LIGHTED 
ROCKEP SWITCH 

n$ vac lighted rocket. 
snap imunu m 
Mi'jcl^-noia 
Orange lens 16 amp 
contact 

MINI-PUSHBUTTON 

S.RS.T. momerilary ^p^jr-Wri 
normally open ie^aaP - 

io S to"a h oo 



NAP ACTION 
SWITCH 



Cherry elect #E-21.N.O.orNC 
0.1A contacts. Suitahle lor alarms 
and other taw enerrjy circuits 
IV lever 

4W EACH 10 FOR $4.20 




TOLL FREE ORDERS ONLY QUANTITIES LIMITED 

1-600 826 5432 MINIMUM ORDER S10. 00 

(ORDER ONLY) USA: S3. 00 SHIPPING 
[IN CALIFORNIA: 1-800-258 6656) FOREIGN ORDERS: 
ALASKA. HAWAII, INCLUDING SUFFICIENT 

OR INFORMATION SHIPPING 

(213)3808000 NOCO.D.' CALIF. RES. ADD 6' a% 



220 Vac 
COOLING FAN 

FtOTRON* 
MX77A3 

Mult.r, XL 
220 Vac 
4 IrB" square 
metal Frame Ear 

CAT* CF-22Q S6.50 ,-:, 
10 lor $60.00 MOO for $500.00 
QUANTITIES AVAILABLE 




CO 

m 

TJ 

-I 

.Tl 
CD 

m 
jj 

<S 
a 



CIRCLE 107 ON FREE INFORMATION CARD 



103 



HE 



STATIC RAMS 



2101 

5101 

2102L-4 

2112 

2114 

2114L-4 

2114L-2 

2114L-15 

TMS4 044-4 

TMM-016-150 

TMM201fi-100 

HM611S-4 

HM6116-3 

HM6116LP.4 

HM6116LP3 

HM6116LP-2 

HM6264P-15 

HM6264LP-15 

HMG264LP-12 



256x4 
256»4 
1024x1 
256x4 
1024x4 
1024x4 
1024x4 
1024x4 
4096x1 
2048x6 
2048x8 
2048x8 
2048x8 
2048x8 
2048x8 
Z04IIB 
B192*8 
B 182x8 
B 182x8 



1450ns) 
(450ns) (CM OS| 

14 !i. In-ill I PI 

{450ml 

(450ns) 

(450m) (LP! 

(200ns)(LP) 

(150ns) (LP) 

(450ns) 

1150ns) 

(100ns) 

(200ni)iCMOS) 

(150ns) (CM 05) 

(200ns) (CM 05) (LP) 

[150ns] (CM 05)[LP) 

(120ns]CCM05][LP) 

(150ns) (CMOS) 

(150n»)(CMOS)(LP) 

(120ns)(CMOS)(LP) 



DYNAMIC RAMS 



4116-250 

4116 200 

4116 150 

4116-120 

MK4332 

4164-200 

4)64-150 

4164-120 

MCM6665 

TMS41G.I 

4164-REFRE5H 

TM 84416 

41128-150 

TMS4464-15 

41256-200 

41256-150 



16394x1 

16364.1 

16384x1 

16384x1 

32768x1 

65538x1 

65535x1 

65535x1 

65536x1 

65536>1 

65536x1 

16384x4 

131072x1 

65536x4 

262144x1 

262144x1 

5v Single 5 Volt Supply 



(250ns) 
[200 ns] 
(150ns) 
1 120ns) 
(200ns) 
(2O0ns)(5v| 
[150ns] (5vl 
[120nsl(5vl 
(200ns) C5vr 
(150ns)(5v) 
[150ns)(5V]|REFH 
[1 50ns|(5v} 
(1 50ns)[5v} 
(150n»H5*> 
(200nsl{5»} 
(150niHS»> 
REFRESH F'i 



1.85 
3.95 

.99 
2.99 

.99 
1.09 
1.49 
1.95 
1.95 
1.49 
1.95 
1.89 
1.95 
1.85 
2.05 
2.95 
3.89 
3.95 
4.48 



1.48 
6.95 
1.19 
1.29 
1,95 
1-95 
1.85 
ESH) 2.85 
4.95 
5.95 
6.95 
2.95 
285 
Refresh 



3MI 



• •••HIGH-TECH**** 
HEGV20 UPD70108 $11" 

REPLACES B0B6 TO SPEED UP IBM PC 10-40% 

* HIGH-SPEED ADDRESS CALCULATION 
IN HARDWARE 

* PIN COMPATIBLE WITH 8088 

* SUPERSET OF 8088 INSTRUCTION SET 

* LOW POWER CMOS 

8 MHZ VZO UPD70 108-8 $13.95 
BMHZ V30 UPD7D116-8 $19.95 

• •••SPOTLIGHT**** 



ORDER TOLL FREE 

800-538-5000 



2708 


1024KB 


I a 50ns) 


4.95 


2716 


2046x6 


|450ns)(5V| 


3.49 


27161 


2046x9 


|350ns)(5V) 


3.95 


TNIS2532 


4096x6 


[4SOns](5Vf 


595 


2732 


4096x8 


<450ns)(5V) 


3.95 


2732A 


4096x8 


[250ns](5VK21V PGM 


3.95 


2732A-2 


4096x8 


(200ns) (5VH21V PGM 


4.2S 


27CS4 


6192x6 


(250ns]|5VHCMOS> 


5.95 


2764 


6192x8 


(450ns]|5V| 


3.49 


2764-250 


3192x8 


(250ns) 1 5 Vf 


3.95 


2764-200 


8192x8 


[200ns] 1 5 Vt 


4.25 


MCM68766 


8182x8 


(35 Oris] 15 VI [24 PIN] 


17.35 


27128 


16384x8 


(250ns)l5VI 


4.25 


27C2S6 


32768x8 


(250ns)|5V)(CMOSI 


10.85 


27256 


32768x8 


(250ns}|5V| 


7.49 


5V= Single 5 Voll Supply 


21V PiiM IW|rim ;,1 21 VGltS 



HSPECTRONICS CDDriM FDRQCDQ 
CORPORATION trifUM tKAbtllo 



. 






mm — _ 


-, — 1 


v — 






V±* 


^M 










T 


MoifeC 


Tirndr 


Capacity 

Chip 


Intensity 
[uW Cm'l 


Unit 
Price 


PE-14 


NO 


$ 


8.000 


583,00 


PE14T 


YES 


a 


6,000 


5119.00 


PE-24T 


YES 


12 


9,600 


M 75,00 [ 



GO 

o 

o 

rr 

H 
O 



o 

< 

EC 



6035 


1.49 


6039 


1.95 


8060 


2.95 


8085 


2.49 


80B7-2 


169.95 


8087 


125.00 


soa a 


635 


sona-2 


5.55 


81L'5 


2.49 


8155-2 


3.95 


8748 


7.95 


8755 


14.95 


B 0286 


129.95 


B0287 


139.35 



8200 




8203 


24.95 


8206 


3.29 


8212 


1.49 


8216 


1.49 


8224 


2.25 


8237 


4 95 


8237-5 


5.49 


8250 


6-95 


8251 


1.59 


8251 A 


1.89 


8253 


1.89 


S253.5 


1,95 


8255 


1.69 


82555 


1.89 


8255 


1.95 


8259-5 


2.29 


6272 


4.95 


8279 


2.49 


8279-5 


2.95 


8282 


3.95 


S284 


2.95 


8286 


3.95 


I 6288 


4.95 



Z-BO 




280- CPU 3 5 MH, 1.69 


4.0 MHZ 


Z80A-CPU 


1.75 


Z8QA-CTC 


1.85 


Z80A-E-ABT 


5.96 


280A-DMA 


5.95 


ZSOAPIO 


1.S9 


ZSOASIO/0 


5.95 


ZSOA-SIO/1 


5.95 


Z80A-5IO/2 


5.95 


6.0 MHZ 


ZSOBCPU 


3,75 


Z80B-CTC 


4.25 


Z80B-PIO 


4.25 


Z80B-DART 


14.95 


Z80B-SlO/0 


12.95 


ZSOBStO/2 


12.95 


L 28671 ZILOO 


19.95 



6500 




1.0MHZ 


1 6502 


2.69 


65C 02 ICMOS1 12.95 


6507 


9.95 


6520 


1.55 


652Z 


4.95 


6526 


26.95 


6532 


6.95 


6545 


6.95 


6551 


5.95 


6561 


19.95 


6581 


34.95 


2.0 MHZ 


| 6S02A 


2.95 


1 6520A 


2.95 


1 652 2 A 


5.95 


6532A 


11.95 


6545A 


7.95 


6551 A 


6.95 


3.0 MHZ 


L S502B 


6.95 



6800 


1.DMHZ 


6800 


1.95 


6802 


4.95 


6603 


9.95 


6809 


5.95 


6809E 


5.95 


6810 


1.95 


EB20 


2.95 


6B21 


1.95 


5940 


6.95 


6843 


13.35 


6844 


12.35 


6845 


4,95 


6B47 


11.95 


EB50 


1.95 


6BB3 


22.95 


2.0 MHZ 


6BBDO 


4.95 


6BB02 


5.95 


6BB09E 


6.95 


6BB09 


6.95 


6BB21 


3.35 


68B45 


6.95 


6SB50 


2.95 


68B54 


7.95 J 



CLOCK 

CIRCUITS 

MM5369 1.95 

MM536S-EST 1.95 
MM58167 12.95 
MM58174 11.95 
. MSM5832 2.95 . 



CRT 




CONTROLLERS | 


1 6645 


4.95 


1 66B45 


8.95 


1 6647 


11.95 


1 KD46505SP 


6.95 


1 MCI 372 


2.95 


1 8275 


26.95 


1 7220 


19.95 


1 CRT5027 


12.95 


1 CRT5037 


3.95 


ITMS9918A 


13.95 J 



DISK 




CONTROLLERS | 


1771 


4.95 


1791 


9.95 


1793 


9.95 


1735 


\? 95 


1797 


12.95 


2791 


19.9S 


2793 


19.95 


2797 


29.95 


6843 


19.95 


8272 


4.95 


UP 0765 


4.95 


MG6976 


12.35 


MB8877 


12.95 


1691 


6.35 


L 2143 


6.95 J 



BIT RATE 

GENERATORS | 


MC14411 
BR1941 
4702 

COM8116 
I MM5307 


9.95 
4.95 
9.95 
9.95 
4.95 J 



r UMTS 




AV5-1013 


3.95 


AV3-1015 


4.95 


TR1602 


3.95 


2551 


4.95 


IM6402 


6.95 


IM6403 


9.95 


INS8250 


6,95 J 



SOUND CHIPS 



r CRYSTALS ' 


32.768 KHz 


.95 


1 1.0 MHr 


2.9S 


1.S432 


2.95 


2,0 


1.95 


2.097152 


1.95 


1 2.457G 


1.95 


3.276E 


1-95 


3.579545 


1.95 


4.0 


1.95 


4.032 


1.95 


5,0 


1.95 


s.ofisa 


1 95 


E.O 


1-95 


G.144 1 


1.95 


6.5536 


1.98 


e.o 


1,95 


10.0 


1 95 


10-738635 


1.95 


12.0 


1.95 


1431S18 


1.95 


15.0 


1 95 


16. Q 


1 95 


17.430 


1.95 


18,0 


1.95 


18.432 


1.95 


20.0 


1.95 


22 11 8-1 


1.35 


20 .0 


1 95 


32.0 


1.55 


CRYSTAL 


OSCILLATORS 


1.0MHz 


5.95 


1.8432 


5.35 


2.0 


5.95 


2.4576 


5.95 


2.5 


4 95 


4.0 


4.95 


5.0633 


4.95 


6.0 


4.95 


6.144 


4.95 


8.0 


4.95 


10.0 


4.95 


12.0 


4.95 


12.480 


4.95 


15.0 


4.95 


16.0 


4.95 


18.432 


4.95 


20.0 


4.95 


1 24.0 


4.95 



M1SC 




TMS99531 


3.95 


TM 593532 


19.95 


ULN2003 


79 


3242 


7.95 


3341 


4.95 


MC3470 


1.95 


MC3-1S0 


8.95 


| MC3487 


295 


11C90 


19.95 


251 3-001 UP 


6.95 


AVS-2376 


11.95 


L AV5-36O0 MIC 11 .95 J 



74LS00 
74LS01 
74LS02 
74LS03 
74LS04 
74LS05 
74LS08 
74LS09 
74LS10 
74LS11 
74LS12 
74LS13 
74LS14 
74LS15 
74LS20 
74LS21 
74LS22 
74L827 
74LS28 
741S30 
741-532 
74LS33 
74LS37 
74LS3B 
74LS42 
74LS47 
74tS48 
74tS51 
74LS73 
74LS74 
74LS75 
74LS76 
74LS83 
74LS85 
74LS8E 
74LS90 
74LS92 
74LS93 
74LS95 
74LS107 
74 LSI 03 
74LS112 
74 LSI 22 
74 LSI 23 
74 LSI 24 
74 LSI 25 
74LS126 
74 LSI 32 
74LS133 
74LS136 
74LS138 
74LS133 
74LS145 
74LS147 
74LS148 
74LS151 
74LS153 
74LS154 
74LS155 
74L51S6 
74LS157 
74LS1S8 
74LS160 
74LS161 
74LS162 
7-1 LSI 63 
L 74LS164 



74LS16S ,85 

74LS166 .95 

74LS169 .95 

74LS173 .49 

74LS174 .39 

74L5175 .39 

74 LSI 91 .43 

74LS192 .63 

74LS193 .69 

74LS194 .69 

74LS195 .69 

74LS196 .59 

74 LSI 97 .59 

74LS221 .59 

74LS240 .69 

74LS241 .69 

74LS242 .69 

74LS243 .69 

74LS244 .69 

74LS245 .79 

74LS251 .49 

74LS253 .49 

74LS256 1-79 

74LS257 .39 

74LS25B .49 

74LS259 1.29 

74LS260 .49 

74LS266 ,39 

74LS273 .79 

74LS279 .39 

74LS2BO 1.98 

74LS2S3 .59 

74LS290 .89 

74LS293 .89 

74LS299 1.49 

74LS322 3.95 

74LS323 2.49 

74LS364 1.95 

74LS365 .39 

74LS367 .39 

74LS368 .39 

74LS373 .79 

74LS374 .79 

74LS375 .35 

74LS377 79 

74LS378 1.18 

74LS390 1.19 

74LS393 .79 

74LS541 1.49 

74LS624 1.95 

74LS640 .33 

74LS645 33 

74LS669 1.23 

74LS670 .89 

74LS682 3.20 

74LS683 3.20 

74L5SB4 3.20 

74LS6B8 2.40 
74LS783 22.95 

81LS95 1.4S 

81LS96 1.43 

81LS97 1.49 

B1LS58 1.49 
25LS2521 2.80 
2SLS2569 2.80 

2ELS31 1.95 

26LS32 1.95 



HIGH SPEED CMOS 




A naw family 


d1 hhgU spetrtT. CMOS logic featuring 1 


Ihx; spcutJ <ti low power 


ScholTk', .dps Ivpicjl gam 1 


proptagaiion delay I . w ■ >f ■■■' ' •■•■ •> ' ■■•■ • ■ ' ' !**• ddvantagos ol | 


CMOS-yeivlo w PCftn*ercotisijrv.plic5R. *uperioi 


noise 1 


Linrrvur.ity. arid imp roved output drive. 






74HC0O 




74HC: Opfir&ie ,ii CMOS logic levels and ant ideal | 


for new, alJ-CMOSdesig 


ns. 




74HP0O 


.59 


74HC1 4B 


1.13 


74HC02 


.59 


74HC151 


.83 1 


74HC04 


59 


74HC154 


2.49 


74HC08 


59 


74HC157 


.89 


74HC10 


59 


74HC158 


.95 


74HC14 


.79 


74HC163 


1.15 


74HC2D 


.59 


74HC175 


.99 


74HC27 


.59 


74HC240 


1.83 1 


74HC30 


.59 


74HC244 


1.89 1 


74HC32 


.69 


74HC245 


1.89 


74HC51 


.59 


74HC257 


.85 1 


74HC74 


.75 


74HC259 


1.39 


74HCS5 


1 35 


74HC273 


1.89 


74HCS6 


69 


74HC299 


4.99 


74KC93 


1.19 


74HC36S 


99 


74MC1 07 


.79 


74HC373 


2.29 | 


74HC109 


.79 


74HC374 


2.29 


74HC1 1 2 


.73 


74HC390 


1.39 


74HC125 


1.19 


74HC393 


1.39 


74WC132 


1.19 


74HC4017 


1.99 


74HC133 


.69 


74HC4020 


1.39 


74HC138 


.38 


74HC4049 


.89 


74HC139 


.93 


74HC405O 


B9 




74HCT00 




74HCT: Dir 


GC1. :!r. ..i 


n replacements Iqt LS TTL 


and enn lie iiitef.Tiij.iHj wsth 74LS in (ha same circuil. | 


74HCTO0 


.69 


74HCT1 66 


3.05 


74HCT02 


.69 


74HCT174 


1.09 


74HCT04 


.69 


74HCT193 


1.33 


74HCT08 


.69 


74HCT1 94 


1.19 


7AHCT10 


69 


74HCT240 


2.19 


7AHCT11 


69 


74HCT241 


2.19 


71HCT27 


.69 


74HCT244 


2.19 


74HCT30 


.69 


74HCT245 


2.19 


74HCT32 


.79 


74HCT257 


.99 


74HCT74 


.85 


74HCT253 


1 .59 


74HCT75 


.95 


74HCT273 


2.09 


74H-CT1 38 


1.15 


74HCT367 


1.09 


74HCT139 


1.15 


74HCI373 


2.49 


74HCT154 


2.93 


74HCT374 


2.49 


74HCT157 


.98 


74HCT393 


1.59 


74WCT158 


.99 


74HCT4017 


2.19 


74HCT161 


1.29 


74HCT4040 


1.59 


74HCT164 


1.39 


74HCT4060 


1.49 1 







74F00 




74F00 


.69 


74F74 .79 


74F2S1 1.59 


74F02 


.69 


74F86 -99 


74F253 1.69 


74F04 


.79 


74F138 1.69 


74F257 1.69 


74F08 


.69 


74 F 139 1.69 


74F280 1,79 


74F10 


,69 


74F157 1.69 


74F2B3 3.95 


74F32 


.69 


74F240 3.29 


74F373 4.29 


L 74F64 


.89 


74F244 3.29 


74F374 4.29 I 



KM 



VISIT OUR RETAIL STORE LOCATEO AT 1256 SOUTH BASCOM AVENUE IN SAN JOSE 
||-^r-) Win* *J ' HOURS. M-W-F. 9-6 TU-TH, 9-9 SAT.9-S 

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TERMS' Minimum order S10 00. For shipping and handling include 52,50 lor UPS 

1224 S. Bascom Avenue. San Jose. CA 951 28 Ground « saso tor ups a„ oi*is o«r i ib and fow^n ordm m 5> ttqum 

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IBM 15 A TRADEMARK OF INTERNATIONAL BUSINESS MACHINES. APPLE 18 A TRADEMARK OF APPLE COMPUTER 



CIRCLE 113 ON FREE INFORMATION CARD 



m 



r 
u. 





CMOS 




4001 


,15 


14419 


4.95 


4011 


.19 


14433 


14.96 


4012 


-25 


4503 


.49 


4013 


.35 


4511 


.69 


4015 


.29 


4516 


.79 


4018 


.29 


4518 


.85 


4017 


.49 


4522 


.79 


4018 


.69 


4528 


.79 


4020 


.59 


4527 


1.95 


4021 


.69 


4526 


79 


4024 


.43 


4529 


2 95 


402S 


.25 


4532 


1.95 


4027 


.39 


4538 


.95 


4028 


.65 


4541 


1.29 


4035 


.69 


4553 


5.79 


4040 


.69 


4585 


.75 


4041 


.75 


4702 


12.95 


4042 


.53 


74C00 


.29 


4043 


.56 


74C14 


.53 


4044 


.69 


74C74 


.53 


4045 


1.98 


74CB3 


1.95 


4046 


.89 


74C85 


1 49 


4047 


.69 


74C95 


.99 


4043 


.29 


74C150 


5.75 


4050 


.29 


74C161 


2.26 


4051 


.69 


74C161 


.99 


4052 


.69 


74C163 


.99 


4053 


.69 


74C164 


i .39 


4056 


2.19 


74C192 


1.49 


4000 


.59 


74C193 


1.49 


4060 


.29 


74C221 


2.49 


4069 


.19 


74C240 


1.89 


4076 


.59 


74C244 


1.89 


4077 


.29 


74C374 


1.39 


40B1: 


.22 


74C905 10.55 


40B5 


.79 


74C91 1 


S.95 


40B6 


.89 


74C917 12.95 


4093 


.49 


74C922 


4.49 


4054 


2.49 


74C923 


4.95 


14411 


9.95 


74C926 


7 95 


14412 


6.95 


80C97 


.95 







7400/9000 




7400 


.19 


74147 


2.49 


7402 


.19 


74148 


1.20 


7404 


.19 


74150 


1.35 


7406 


.29 


74151 


.55 


7407 


.29 


74153 


.55 


7409 


.24 


74154 


1.49 


7410 


.19 


74155 


.75 


7411 


.25 


74157 


.55 


7414 


.49 


74159 


1.65 


7416 


.25 


74161 


.69 


7417 


.25 


74163 


.69 


7420 


.19 


74164 


.85 


7423 


.29 


74165 


.85 


7430 


.19 


74166 


1.00 


7432 


.29 


74175 


.89 


743 S 


.29 


74177 


.75 


7442 


.49 


74178 


1.15 


7445 


.69 


74181 


2.25 


7447 


.83 


741 B2 


.75 


7470 


.35 


74184 


2.00 


7473 


.34 


74191 


1.15 


7474 


-33 


74192 


.79 


7475 


.45 


74194 


.85 


7475 


.35 


74196 


.79 


7483 


.50 


74197 


.75 


7485 


.53 


74199 


1.35 


7486 


.35 


74221 


1.35 


7499 


2.15 


74246 


1.35 


7490 


.39 


74247 


1.25 1 


7492 


.50 


74248 


1 85 


7493 


.35 


74249 


1.95 


7495 


.55 


74251 


.75 1 


7497 


2.75 


74265 


1.35 1 


74100 


2.29 


74273 


1.95 1 


74121 


-29 


74278 


3 11 1 


74123 


.49 


74367 


.65 1 


74125 


.45 


74368 


.65 1 


74141 


.65 


9968 


3.95 1 


74143 


5.95 


9602 


1 DO 


74144 


2.95 


9637 


2 95 


74145 


.60 


96502 


1.96 J 



74S00 



74S00 

74S02 

74S03 

74S04 

74505 

74S08 

74S10 

74815 

74830 

74S32 

74S37 

74538 

74S74 

74885 

74886 

74S112 

74S124 

74S138 

746 140 

74S151 

748153 

748157 

74S15B 

74S161 



745 163 
745 168 
748174 
748175 
74S188 
748189 
745195 
745196 
74S197 
748226 
748240 
748241 
745244 
745257 
745 25 3 
748258 
74S280 
748287 
745288 
745299 
74S373 
748374 
74S471 
745571 



[ DATA ACQ 


interface] 


! ADC0300 15 55 


ST2G 


1.29 


ADC0S04 3.49 


3T2S 


1.29 


ADC0809 4.49 


BT35 


89 


ADC0816 14,95 


arse 


89 


ADC0817 9.95 


3T97 


.59 


A DC 0831 395 


8T98 


.89 


DACDSOG 4.45 


DM8131 


2.95 


OACOBDG 1.35 


DP8303 


2.29 


DACOBOH 2.35 


DS8833 


2.25 


DAC102D 3,25 


DS8835 


1.99 


DAC1022 5.95 


DS8S36 


.99 


lv MC140&L& 2.95 


DSS837 


1.65 J 



EDGECARD CONNECTORS | 


100 


PIN ST 


6100 


.125 


3.95 


100 


PIN WW 


S-100 


.125 


4.95 


62 


PIN 5T 


IBM PC 


TOO 


1.95 


50 


PIN ST 


APPLE 


.100 


2.95 


44 


PIN ST 


STD 


.156 


1.95 


44 


PIN WW 


STD 


.156 


4.95 J 



36 PIN CENTRONICS 




MILE 




1 IDCEN36 RIBBON CABLE 


6.95 


1 CEN3S SOLDER CUP 


4.95 


Ft MILE 




1 IOCEN36 F RIBBON CABLE 


7.95 


I CEN36PC RT ANGLE PC MOUNT 


4.95 J 



INTERSIL 



ICL7106 
I C 17107 
ICL7GS0 
lC 1*038 
1CM7207A 
L 1CM720B 



VOLTAGE 
REGULATORS 

TO-220 CASE 

7805T .49 7905T ,59 

790ST .49 790BT .59 

7812T .43 791 2T .59 

78 1ST .49 791 5T .59 

TO-3 CASE 

780SK 1.53 7905 K 1.69 

7812K 1.33 731 2K 1.49 

TO-93 CASE 
78L05 .49 79L05 .63 
78L12 49 79L12 1.49 

OTHEH VOLTAGE REGS 
LM323K 5V 3A TO-3 4.79 
LM32BK Adj 5A TO-3 3-95 
78H05K 5V 5A TO-3 7.95 
78H12K 12V 6A TO-3 8.95 
. 78P05K 6V 10A TO-3 14.95 , 



riC SOCKETS 








1-9S 


100* 


9 PIN ST 


.11 


.10 


14 PIN ST 




11 


.08 


16 PIN ST 




12 


.10 


18 PIN ST 




16 


.13 


20 PIN ST 




IB 


.15 


22 PIN ST 




15 


.12 


24 PIN ST 




20 


.15 


28 PIN 5T 




22 


.16 


40 PIN ST 




3(1 


.22 


64 PIN ST 


1 


ill 


1.49 


5T=S0I-DERTAII 




8 PIN WW 


.59 


.69 


14 PIN WW 


.69 


.52 


16 PIN WW 


.69 


-5B 


' 18 PIN WW 


.99 


.90 


20 PIN WW 


1.09 


.98 


22 PIN WW 


1.39 


1.25 


24 Plftl WW 


1.49 


1.35 


28 PIN WW 


1 63 


1.49 


40 PIN WW 


1.99 


1 80 


WW WIRE WRAP 




16 PtN ZIF 


4 95 


CALL 


21 PIN ZIF 


5.95 


CALL 


2B PIN ZIF 


6.95 


CALL 


40 PHY ZIF 


9 95 


CALL 


ZIF^TEXTOOL 




L 1ZERO INSERTION FORCE* 





LINEAR 




TL066 


-99 


L.M733 


.98 


TL071 


.69 


LM741 


.29 


TL072 


1.09 


LM747 


.89 


TL074 


1.95 


LM74B 


.59 


TL0B1 


.59 


MC1330 


1.69 


TL082 


.99 


MC1350 


1.19 


turn 


1.49 


MCI 372 


6.95 


LM301 


.34 


LM1414 


1.53 


LM303K 


1.26 


LM145S 


.49 


LM311 


.59 


LM1488 


.49 


LM311H 


.89 


LM1489 


.49 


LM317K 


3.49 


LM1496 


.85 


LM317T 


.95 


LM1812 


8.25 


LM31B 


1.49 


LM18B9 


1.95 


LM319 


1.25 


ULN2003 


.73 


LM320 14*7900 


XR220S 


3.95 


LM322 


1.95 


XR2211 


2.95 


LM323K 


4.75 


XR2240 


1.95 


LM324 


.49 


MPO2907 


1.95 


LM331 


3.95 


LM2917 


1.35 


LM334 


1.19 


CA304G 


.63 


LM335 


1.79 


CA30B1 


.99 


LM336 


1.75 


CA3082 


.99 


LM337K 


3.95 


CA3086 


.80 


LM33SK 


6.95 


CA30S9 


1.95 


LM339 


.59 


CA3130E 


.33 


LM340 IO.7800 


CA3146 


1-23 


LM350T 


4.60 


CA31 80 


1.19 


LF353 


.59 


MC3470 


1.95 


LF356 


.99 


MC3480 


8.95 


LF357 


99 


MC3487 


2.95 


LM35B 


.59 


LM3900 


.43 


LM380 


.89 


LM3909 


.98 


LM3S3 


1.95 


LM391 1 


2.25 


LM3S6 


.89 


LM3914 


2.38 


LM393 


.45 


MC4024 


3.49 


LM394H 


5.95 


N1C4044 


3.99 


TL494 


4.20 


RC4136 


1.25 


TL497 


3.25 


RC455S 


.69 


NE555 


.29 


LM 13600 


1.49 


NE558 


.49 


75107 


1.43 


NE558 


1.29 


75110 


1.35 


NE564 


1.95 


75160 


1 95 


LM565 


95 


75154 


135 


LMSM 


1.49 


75188 


1.25 


LM567 


.73 


75183 


1.25 


NE570 


2.95 


75451 


.39 


NE590 


2.50 


75452 


.33 


NE592 


.98 


75453 


.33 


LM710 


.75 


75477 


1.23 


LM723 


.49 


75492 


79 


H.TO-5 CAN, K=TO-3. T=T0-220 J 



DIP CONNECTORS 



DESCRIPTION 



HIGH RELIABILITY TOOLED 
ST IC SOCKETS 



HIGH RELIABILITY TOOLED 
WWIC SOCKETS 



COMPONENT CARRIES 
|OIP HEADERS] 



RIBBON CABLE 
DIP PLUGS [IDC) 



ORDER BY 



AUGATxxST 



AUGATxxWW 



for onorwivG instructions see o-subminia tube below 



M i ' I I I I I I I ■ 

AUGAT245t 





D-S 


UBMINIfl 


TURI 


: 










DESCRIPTION 


ORDER BY 


CONTACTS 


9 


15 


19 


25 


37 


50 


SOLDER CUP 


MALE 


D8*xP 


52 


.90 


1.25 


1.25 


1 80 


3.4a 


FEMALE 


DSxxS 


95 


1.15 


1.50 


1.50 


2 35 


4 32 


RIGHT ANGLE 
PC SOLDER 


IY1A1E 
FEMALE 


DBkxPR 


1.20 


1.49 


m 


1.95 


2 65 


-Er 


DBkxSR 


1 25 


1.55 


— 


;: oo 


2.79 


wim: WRAP 


_MAL£ 

"female 


DSxxPWW 
DBxxSWW 


1.63 


2.56 




3.89 
6.84" 


5 60 

9.95 


-=r 


2.75 


4.27 


... 


3 DC 
RIBBON CABLE 


MALE 
FEMALE 


IDBkkP 
IDBxxS 


2.70 


2.95 


m 


3.98 


5 70 


.„ 


2.92 


3.20 


— 


4.33 


6 76 


„. 


HOODS 


METAL 

<>RtY 


MHOQOkk 
HOODkx 


1 25 


1.25 


1.30 


1.30 






65 


.65 


... 


.65 


.76 


.95 





r y. n — M 



ORDERING INS TRttCTlONS: iNSERT THE NUMBER OF CONTACTS IN THt. PO^i TiON 

MARKPD~jtK Qr THE ■'ORDER BY' PART NUMBER USTEP 

EXAMPLE- A 15 PIN HfGH T ANGL € MALE PC SQLQEH WOULD BE DBlhPR 



MOU NTING HARDWARE $1.0 
IDC CONNECTORS 




111 SCfllPTION 



SOLDER HEADER 



RIGHT ANGLE SOLDER HEADER 



WW HEADER 



RIGHT ANGLE WW HEADER 



HIBBON HEADER SOCKET 



RIBBON HEADER 



RIBBON EDGE CARD 



I DS xx 
IDMxx 



82 1.29 1.68 2.20 



1.75 2.25 2.65 2.75 




FOB ORDERING INS TffllKltOHS SEE ll-SUBMINIA TUBE ABOVE 




HARD TO PINO 

"SNAPABLE" HEADERS 

CAN BE SNAPPED APART TO 

MAKE ANY S12E HEADER. 

ALL WITH .1" CENTERS 

1 ..-'.0 STRAIGHT LEAD .99 

1*40 RIGHT ANGLE 1.49 

2x40 STRAIGHT LEAD 2,49 

2x40 RIGHT ANGLE 2 99 , 



SHORTING 
BLOCKS 

GOLD / \ 

CONTACTS / \ 

SPACED / \ 

AT.1" I \ 

CENTERS |^0 

L 5/$l.O0 



Dear Wr Rose . 

I feel compel led to cairenend yju and your people 
for the pleasant, polite, wil 1 tugncaa to help and 
professional attitude you have di»pl &yed , In 
these t ime-a 1 1 is indeed refreshing to deal wi th a 
company whose staff conaiats of people of this 
caliber. My frleiids arid associates will most 
certainly be doing business: wi Ml you again, 

Sincerely, N l ch ■» I aa Chabra 



DI0DES/0PTO/TRANSISTORS 



1N751 
1N75S 
1N4148 
1N4004 
IN 5402 
KBP04 
KBU3A 
MDA990-2 
N2222 
PN2222 
2 N 2905 
2N2907 
2N3055 
. 2 N 3904 



25/1.00 

10/1.00 

.25 



4N26 

4N27 

4N28 

4N33 

4N37 

MCT-2 

MCT-6 

TIL 111 

2N3906 

2N4401 

2 N 4402 

2N4403 

2N6045 

TIP31 



LED DISPLAYS 






END-3571359) 


COM CATHOOE 


.362' 


1.25 


FND-5001503) 


COM CATHODE 


.5" 


1.49 


FND-507J51O] 


COM ANODE 


fi" 


1.49 


MAN-72 


COM ANODE 


.3" 


.99 


MAN. 74 


COM CATHOOE 


.3" 


.99 


MAN8940 


COM CATHODE 


.8" 


1.99 


TIL-313 


COM CATHOOE 


.3" 


.45 


HP5082-7760 


COM CATHOOE 


43" 


1.29 


T1L-311 4x7 H EX W LOGIC 


770' 


9.95 


HP5082-7340 4x7 HEXW/LOGIC 


290' 


7.95 


DIFFOSED LEDS 1-39 


100- UP 


JUMBO RED 


T1'/. 10 




.09 


JUMBO GREEN 


TI W .14 




12 


JUMBO YELLOW 


T1"/i .14 




.12 


MOUNTING HOW 


T1V. .10 




.09 


l MINI RED 


TI .10 




.09 





SWITCHES 




SPOT MINI-TOGGLEON-ON 
DPDT MINI TOGGLE ON ON 
DPDT MINI. TOGGLE ON -OFF -ON 
SPST MINI. PUSHBUTTON NO, 
SPST MINI-PUSHBUTTON N.C. 
SPST TOGGLE ON -OFF 
BCD OUTPUT 10 POSITION 6 PIN DIP 


1.25 

1.50 
1.75 
.39 
.39 
.49 
1.95 




DIP SWITCHES 




4 POSITION ,85 7 POSITION 

5 POSITION .90 8 POSITION 
[6 POSITION .90 10 POSITION 


.35 

95 

1.28 



RIBBON CABLE 


CONTACTS 


SINGLE COLOR 


COLOR CODEO 


V 


10' 


r 


10' 


10 


.18 


1,60 


.30 


2.75 


16 


.28 


2.50 


.48 


4.40 


20 


.36 


3,20 


.60 


5.50 


25 


.45 


4.00 


.75 


B B5 


26 


.46 


4.10 


.78 


7.15 


34 


.61 


5.40 


1.07 


9.35 


40 


.72 


6.40 


1 20 


11,00 


50 


.89 


7.50 


1.50 


13,25 



CALL FOR VOLUME QUOTES © copyright isb6 jdh micro-devices 



CIRCLE 177 ON FREE INFORMATION CARD 



03 

m 

TI 



LTJ 

m 



CD 

00 
01 



105 



'JilAlillHilililM 

BARGAIN HUNTERS CORNER 



OH PC USERS! 



EEZ 




* SHOCK MOUNTED FOR 80 Gs- 
IDEAL FOR PORTABLES! 

* MMI MODEL MM212, 'A HEIGHT, 

* INCLUDES CONTROLLER, CABLES 
& INSTRUCTIONS FOR IBM 

WIRELESS KEYBOARD 

* MADE BY CHERRY FOR IBM PC & PCjr 

* OPERATES UP TO 40 FEET FROM COMPUTER 

* INFRARED RECEIVER FOR PC/XT INCLUDED 

HURRY— QUANTITIES ARE LIMITED! 
SPECIALS END 8/31/86 



PACE WIRE WRAP WIRE 

PRECUT ASSORTMENT 

IN ASSORTED COLORS 327.50 

"IQOea: 5.5". 6.0", 6-5", 7.0" 
2S0on: 2.5". 4.5". 5.0" 
50DDa: 3,0", 3,5". 4.0" 



100 feet $4.30 250 fool S7.25 

500 foot SI 3.25 1000 feat 92 1.05 

Please specify color: 
Blue. Black. Yellow or Red 



WIRE WRAP PROTOTYPE CARDS 

FR-4 EPOXY GLASS LAMINATE 
WITH GOLD-PLATED EDGE-CARD FINGERS 



tjnjDRnMvitv'jH 




EMI FILTER 



■ MANUFACTURED yf >J 
BY CORCOM ^55= K 

- low cost *r?3R- J 

• FITS LC-HP BELOW l ^J i,) 

■ 6 AMP 120/240VOLT ^^A^ 

6 FOOT LINE CORDS 

LC-2 2 CONOUCTOfi .39 

LC-3 3 CONDUCTOR .99 

LC-HP 3 CONDUCTOR W STO 

FEMALE SOCKET 1.49 

MUFFIN FANS 

3.15" SO ROTRON 14.95 

3.63" SO ETRI 14.95 

,3.18" SO MASUSHITA 16.95, 



IBMPH2 ._-. 

IBM 

BOTH CARDS HAVE SILK SCREENED LEGENDS 

AND INCLUDES MOUNTING BRACKET 

IBM-PR1 WITH -5V AND GROUND PLANE ....$27.95 

I B M PR Z A s A r II .)V r VJ I T II [) f C. f) I N G I A V UT 929.95 

S-100 

P1Q0-1 BARE MO FOIL PADS ., S1S.15 

P1GD-2 HORIZONTAL BUS S21-S0 

PI 00-3 VERTICAL BUS 521.80 

P1Q0-4 SINGLE FOIL PADS PER HOLE $22.75 

APPLE 

P500-1 BARE NO FOIL PADS $15.15 

P500-3 HORIZONTAL BUS $22.75 

P500-4 SINGLE FOIL PAOS PER HOLE $21.80 

7060-35 FOR APPLE Mo AUX SLOT ....,,.,, $30-00 



SOCKET-WRAP 1.0 ™ 

i SLIPS OVER WIRE WRAP PINS 

■ IDENTIFIES PIPd NUMBERS ON WRAP 

SIDE OF BOARD 
' CANWRTTE ON PLASTIC; SUCH AS IC 
PINS PARTfl 

8 IDWflAPOS 

14 IDWRAP14 
16 IDWHAJMG 

15 IDWHAP1B 
20 IDWRAP20 
22 IDWHAP22 
24 IDWPAP 24 
28 IDWRAP28 
40 ID WRAP 40 

PLEASE ORDER BY NUMBER OF 
PACKAGES ,PCK. OFf 




FRAME STYLE 
TRANSFORMERS 



25PIND-SUB 
GENDER 
CHANGERS >- 

$7.95 



SWITCHING POWER SUPPLIES 





CAPACITORS 








TANTALUM 






%Api 


15V 


.35 


.47bI 


35V 


.45 


SB 


15V 


.70 


1.0 


35V 


.45 


10 


15V 


SO 


2.2 


35V 


.65 


22 


15V 


1.35 


4,7 


35V 


.86 


.22 


3SV 


.40 


10 


35V 


1 00 






DISC 






1 10|il 


50V 


.05 


630 


50V 


.05 


2Z 


50V 


.05 


.00 V 


50V 


.05 


27 


50V 


.05 


0022 


50V 


US 


33 


50V 


.05 


.005 


50V 


05 


47 


50V 


.05 


.01 


50V 


.07 


68 


50V 


.05 


-02 


50V 


07 


100 


50V 


.05 


.05 


50V 


.07 


220 


50V 


.05 


.1 


12V 


.10 


560 


50V 


.05 


.1 


50V 


12 




MONOLITHIC 






,01(il 


50V 


.14 


.V 


50V 


-13 


.047/if 


50V 


.15 


.47;d 


50V 


.25 




ELECTROLYTIC 




RADIAL 




AXIAL 




\,i\ 


25V 


.14 


llil 


50V 


.14 


2.2 


35V 


.15 


10 


50V 


.16 


4.7 


50V 


.15 


22 


16V 


.14 


10 


50V 


.15 


47 


50V 


.20 


47 


35V 


-18 


100 


35V 


25 


100 


16V 


-IB 


220 


25V 


.30 


220 


35V 


.20 


470 


50V 


.50 


470 


25V 


.30 


1000 


1SV 


.60 


2200 


16V 


.70 


2200 


16V 


70 


I 4700 


25 V 


1.45 


4700 


1SV 


1 25 1 



DATARASE EPROM ERASER $34.95 



. ERASES 2 IN 10 MINUTES 
■ COMPACT-NO DRAWER 
. THIN METAL SHUTTER 

PREVENTS UV LIGHT 

FROM< ESCAPING 



1/4 WATT RESISTORS 

5% CARBON FILM ALL STANDARD VALUES 
FROM 1 OHM TO 10 MEG. OHM 

10 PCS samev**- .05 100 PCS HUM y*^ .02 

, SO PCS w<- -..v..*- .025 1000 PCSanwIUfl -015 





RESISTOR NETWORKS 




StP 


10 PIN 


9 RESISTOR 


.69 


SIP 


8 PIN 


7 RESISTOR 


.59 


DIP 


16 PIN 


8 RESISTOR 


1.09 


DIP 


16 PIN 


15 RESISTOR 


1.09 


DIP 


14 PIN 


7 RESISTOR 


.99 


[dip 


14 PIN 


13 RESISTOR 


.99 



DIMENSIONS 



DISTRIBUTION 
STHIPtS] 



SPECIALS ON DYPASS CAPACITORS 

.01 {A CERAMIC DISC 100/S5.00 

.01 iA MONOLITHIC 100/S10.00 

.1 fit CERAMIC DISC 100/S6.50 

.1 /jf MONOLITHIC 100/S12.50, 



BREADBOARDS 



■ FOR IBM PC-XT COMPATIBLE 

■ 135 WATTS 

' -5Vfi ISA, 12V f" 4.2A PS-IBNI 
-Wn' .5 A. -12V 'j .5 A 

* ONE YEAH WARRANTY 

PS-IBM -150 $79.95 

. FOR IBM PC-XT COMPATIBLE 
- 150 WATTS 

* -12V- 5.2A, -SVlr 16A 
-12V w 5A. -5Vn -5A PS 130 

■ ONE YEAR WARRANTY 

PS-130 $99.95 

* 1 30 WATTS 

* SWITCH ON REAR 

■ FOR USE IN OTHER IBM 
TYPE MACHINES 

* 90 DAY WARRANTY PS -A 



- USE TO POWER APPLE TVPE 

SYSTEMS 
• >5Vfti 4A, 12V tp 2 r 5A 

-6V> 5A. -12V :i .5 A 

■ APPLE POWER CONNECTOR 

PS-SPL20D $49.95 

■SV(u'25A, -12V U 3.5A 
-5V[*r' IA, -12V p. IA 

■ UL APPROVED 

■ ALUMINUM ENCLOSURE 



BOOKS bt STEVE CIARCIA 

uu.li u YOUH OWN 

Z30 COMPUTER S1S 

CIRCUIT CELLAR VOL 1 $17.95 

CIRCUIT CELLAR VOL 2 $1 B.95 

CIRCUIT CELLAR VOL 3 $18.95 

CIRCUIT CELLAR VOL 4 $18.95 

. CIRCUIT CELLAR VOL 5 $19.95 , 



t**. .r est 




MICROCOMPUTER 

HARDWARE HANDBOOK 

FROM ELCOMP $14.95 

OVER 800 PAGES OF DATA SHEETS 
ON THE MOST COMMONLY USEO 
IC$. INCLUDES TTL. CMOS, 74LS0O, 
MEMORY, CPUs. MPU SUPPORT. 
LAND MUCH MORE' 




LITHIUM BATTERY 

i ASUSED IN CLOCK CIRCUITS 




3 VOLT BATTERY 93.95 

t BATTEHY HOLDER 41.49 



HEW EDITION! 

1986 
IC MASTER 

THE INDUSTRY STANDARD 

$129.95 



en 
o 

z 
o 

EC 

r- 

o 



o 

< 

rr 



VISIT OUR RETAIL STORE LOCATED AT 1256 SOUTH BASCOM AVENUE IN SAN JOSE 

— «.— . m. mm ■ HOURS: M-W-F. 9-6 TU-TH. 9-9 



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resident rnusl include applicable sain lai. All merchandise u warranted tor 90 day*. 
unless otherwise staled Pnces are sub|«l to change wilhoul nolice We ore nol 

it quantities and lo 
handiw subject to pMOr sale 



© COPYRIGHT 1986 JDR MICRODEVICES 

THE JDR MICRODEVICES LOGO IS A REGISTERED TRADEMARK OF JDR MICRODEVICES JDR INSTRUMENTS AND JDR MICRODEVICES ARE TRADEMARKS OF JDH MICRODEVICES 

IBM IS A TRADEMARK OF INTERNATIONAL BUSINESS MACHINES APPLE IS A TRADEMARK OF APPLE COMPUTER 



106 



CIRCLE 178 ON FREE INFORMATION CARD 



DISK DRIVES 

FOR APPLE COMPUTERS 



AM 50 
$99.95 



' v, HT, DIRECT DHIVE 

i 1QQ% APPLE COMPATIBLE 

•r SIX MONTH WARRANTY 



BAL-500 
$129.95 



- TEAC MECHANISWI D3H6CT DRIVE 
i 100% APPLE COMPATIBLE 
r FULL ONE YEAR WARHANTV 



flP-135 
$129.95 



t FULL HT SHUGAHT MECHANISM 
x DIRECT REPLACEMENT FOR APPLE 

DISK II 
t SIX MONTH WARRANTY 

MAC535 
$249.95 L 

* 3.5" ADD- ON DISK DRIVE 

* 100% MACINTOSH COMPATABLE 

■ DOUBLE SIDED SOOK BYTE STORAGE 

* HIGH RELIABILITY DRIVE 
HAS AUTO-EJECT MECHANISM 

* FULL ONE YEAR WARRANTY 



AD-3G 
$139.95 



Lfe^j) 



- 100ft APPLE lie COMPATIBLE, 

READY TO PLUG IN, W- SHIELDED 

CABLE & MOLDED 13 PIN 

CONNECTOR 
« FAST, RELIABLE SLIMLINE DIRECT 

DRIVE 
* SIX MONTH WARRANTY 

DISK DRIVE ACCESSORIES 

FDD CONTROLLER CARD S49.95 
He ADAPTOR CABLE S19.95 

ADAPTS STANDARD APPLE DRIVES 
FOR USE MTU APPLE lie 



KB- 1000 



$70.05 



CASE WITH KEYBOARD 
FORAPPLE TYPE MOTHERBOARD 
' USER DEFINED FUNCTION KEYS 
■ NUMERIC KEYPAD WITH 

CURSOR CONTROL 
• CAPS LOCK . AUTO-REPEAT 



KEYBQARD-AP $49.95 1 

• REPLACEMENT FOR APPLE II 

KEYBOARD 
. CAPS LOCK KEY. AUTO-REPEAT 
r ONE KEY ENTRY OF BASIC 

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V 



EXTENDER CARDS 

IBM-PC $45.00 

1BM-AT $68.00 

APPLE II $45.00 

APPLE He $45.00 

MULTIBUS $86.00] 



APPLE COMPATIBLE 
INTERFACE CARDS 

EPfiOM PROGRAMMER $59.95 

I 



O 9 ' £0o 



MODEL 
RP5Z5 



■ DUPLICATE OH BURN ANY 
STANDARD 27s» SERIES EPROM 

■ EASY TO USE ME NU-DRIVEN 
SOFTWARE IS INCLUDED 

■ MENU SELECTION FOR 271 6, 
2732. 2732 A. 2764 AND 271 28 

' HIGH SPEED WRITE ALGORITHM 

■ LED INDICATORS FOR ACTIVITY 

■ NO EXTERNAL POWER SUPPLY 
NEEDED 

■ ONE YEAR WARRANTY 



16K RAMCARD 



$39.95 



' FULL TWO YEAR WARRANTY 
' EXPAND YOUR 4SK APPLE TO 
64K 

' USE IN PLACE OF APPLE 
LANGUAGE CARD 

BAHE PC am W/IMSTHUCTIOHS S9.95 



ID TEST CARD 



$99.95 



. QUICKLY TESTS MANY COMMON 

ICt 
< DISPLAYS PASS OR FAIL 
• ONE YEAR WARRANTY 
. TESTS: 3000 SERIES CMOS. 
7-1HC SERIES CMOS. 
7400. 74LS. 74L. 74H & 74S 



3DQB MODEM $49.95 

FOR APPLE OR IBM 

INCLUDES ASCII PRQ-EZSOP TWAP.E 



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[JOYSTICK lir-401 $7.95 

FOR ATARI 400, 800, 2600, 
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DISKFILE 

HOLDS 70 5M" DISKETTES 



3.5" DISKFILE holds 40 $9« 



POWER STRIP 



Ul Apf'liOVLO 
. 15A CIRCUIT 
BREAKER 



$12.95 



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I SERIAL OR PARALLEL 
I CONNECTS 3 PRINTERS TO ONE 
C OM P U T L P. G R V I C E V E F! S A 

■ ALL LINES SWITCHES 

• HIGH QUALITY ROTARY SWITCH MOUNTED 

ON PCB 
' GOLD CONTACTS 

■ STURDY METAL ENCLOSURE 



V 



SWITCH-3F CENTRONICS PARALLEL S99.S5 
[ SWITCH3S RS232 SERIAL $99.95 J 

M, PRINTER BUFFERS 

■ FREES COMPUTER FOR OTHER TASKS 
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* ALL MODELS FEATURE PRINT PAUSE 
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SP120P PARALLEL $139.95 

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SP120S RS232 SERIAL $159.95 

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SP110P PARALLEL $249.95 

i 64K UPGRADABLE TO 512K 

■ SPOOLS OUTPUT OF UP TO 3 COMPUTERS 

■ LED BARGF1APH DISPLAYS AMOUNT OF 
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DATA IN BUFFER ^^^_ , 

■ REPEAT FUNCTION CAN 
PRODUCE MULTIPLE 
COPIES OF A DOCUMENT 



Am 



NASHUA DISKETTES DEALS 

5V," SOFT SECTOR 
DS.DD WITH HUB RINGS 

$990 690ea 59Cea 

BOX OF 10 BULK QH 50 SULK QTt 250 

NASHUA DISKETTES WERE JUDGED 

TO HAVE THE HIGHEST POLISH 

AND RECORDED AMPLITUDE OF ANY 

DISKETTES TESTED ACCORDING TO 

"COMPARING FLOPPY DISKS". BYTE 9-'S4 





DISKETTES 






NASHUA 51/4" 




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CSBUPPLE $24.95 

APPLE TYPE CABINET W/QUT POWER SUPPLY 

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FULL HT BW* BEIGE CABINET W/POWER SUPPLY 

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DUA L FUL L HT 8 ' CABINET W-- POWER SUPPLY 






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TEST EQUIPMENT FROM JDR INSTRUMENTS 
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$54.95 



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■ FAST, AUDIBLE CON- 
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20MHZ DUAL TRACE OSCILLOSCOPE 
35MHZ DUAL TRACE OSCILLDSCDPE 



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FOR MOHE INFORMATION ON THE OSCILLOSCOPES. CALL US FOR FHEE PRODUCT BRIEFS. 



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I $129.85 

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IBM COMPATIBLE KEYBOARDS 
DKM-2000 $59.95 IBM-5151 $79.95 




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Toll Free 800-538-5000 ■ (408) 995-5430 • FAX (408) 275-8415 • Telex 171-110 



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) COPYRIGHT 1986 JDR MICRODEVICES 



TENMfit 



THE NAME YOU CAN 
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TEST EQUIPMENT 




1 

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faSuBt 35MHz Dual Trace 
Oscilloscope 

■ Two high quality 10:1 probes included 

■ For additional specification see MCM 
Catalog SI 2 
£72-330 



$569?.? 




TEMM4P 20 MHz Dual Trace 
Oscilloscope 

■ Two high quality 10:1 probes included 

■ For additional specification see MCM 
Catalog #12 

#72-320 




*389?5 




TENMd* 3 1 A Digit LCD Multimeter 

■ Measures resistance. AC-DC voltage and 
current ■ Diode and hFe transistor tests 

■ Overload protection ■ 10Mohm input 
impedance ■ Carrying case included 

#72-050 



•" — 




TEMUP 

30A 

Power Supply 

■ Output voltage: 1-1SVDC ■ Lighted crass 
needle meter: Displays voltage, current and 
power simultaneously ■ Output current: 30A, 22A 
continuous ■ Fan cooled 

#72-035 




$ 39S? 




$ 199°° 



ltMHMfr Combination Function 
Generator and Frequency Counter 

■ 6 digit display ■ Output range: 2Hz-2MHz: seven 
ranges ■Counter range: 1Hz-10MHr bS-ISV TTL 
and CMOS output ■ Wave forms: sine, triangle, 
square, pulse, and ramp, 
#72-380 



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' ** Hl^^ Power Supply 

■ Regulated outputs — constant volt or constant 
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#72-420 



$995? 



1 



TENM4* Digital Capacitance Meter 

■ Measurement range from 0.1 pF to 19.999fiF 

■ Sampling time: .5 seconds ■ Accuracy: ± 1% 
full scale ■ Checks capacitors in or out of circuit 

■ Carrying case included 

#72-040 

SCQiO 

a '»(ea.) 



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(2-up) 



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ISW Frequency Counter 

■ 8 digit LED display ■ Measurement range 
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#72-375 




$189?„5 



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XT 

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February 1984 article on building your own Cable TV Descrambler. 

*701 PARTS PACKAGE $29.95 

Includes all the original resistors, capacitors, diodes, transistors, 
integrated circuits, coils, IF transformers {toko BKAN-K5552AXX). 

*702 PC BOARD $12.95 

Original etched & drilled silk-screened PC board used in the article. 

*704 AC ADAPTOR $ 12.95 

Original (14 volts DC @ 285ma) ac adaptor used in the article. 

S n P°E D C D I D A D L D S 

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Add $2.50 shipping and handling — $4.50 for Canadian orders 
We also offer quantity Discounts on 5 or more units 



^JIj^J^J Reprint of Radio Electronics article (February 1984) on Building Your 
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60-CHANNEL 

CABLE 
CONVERTER 

WITH INFRARED REMOTE CONTROL 

SC-60R CONVERTER 5 69.95 

Thousands of these converters sold nationally for $119.95 
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All converters are NEW, with Full manufacturer's WARRANTY. 
FEATURES: 

□ Full 60 Channel Capability 

D Cordless Infrared remote control 

□ Ultra-Stable Synthesized tuning 
D Microprocessor controlled PLL 

□ Works on all TV models, channel 3 output 

□ Standard/ HHC Switch for compatibility 
with all Cable Systems 

D Will work with all types of external descramblers 

Add $3.50 Shipping and Handling 
$4.50 on Canadian Orders 



ORDER 

TOLL FREE 

1-800-227-8529 

inside MA 617-695-8699 
VISA, MASTERCARD or C.O.D. 



ilia 

€L€CTROfllCS,lflC 

6 Wilkins Dr., Suite 207 
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SERVICE CHARGES VOLUME DISCOUNT 



ID QIGIKfr. PQ flia iit 1h-»f Hi*n ,iMi Ml bfJDl 



CIRCLE B2 ON FREE INFORMATION CARD 



ADVERTISING INDEX 



RADIO-ELECTRONICS does not assume any responsibility for errors that may appear in the index below. 



Free 
SI 

108 

76 

107 

187 

84 
197 

77 

53 
98 
85 
109 



182 
89 

79 
205 

125 
192 

127 
9S 



Information Number Page 

A.l.S. Satellite 77 

AMC Sales 9(1 

AP Products 34 

Ail Electronics 103 

All-Crystal Displays 76 

AmazinB Devices 98 

Appliance Service 76 

Augal 38 

ll&K Precision 26 

HP CV3 

BUYtIS 77 

Beckman Industrial 79 

Blue Star Industries 77 

C & S Sales 71 

C.O.M.B 27 

CIE IB 

Craig Laboratories 22 

Cameo Enterprises 1 14 

Command Productions 93 

Communications Electronics 3 

Cook's institute . 9 3 

Coop's Satellite Digest 73 

Copper Electronics 22 

Crosley 77 

Deco Industries 76.77 

Dick Smith Electronics 1 10.1 1 1 



82 
204 



120 

IS6 

111,176 

100 

121 



196 



62 

86 

195 

65 

59 

113,177 

178,179 

180 

114 

115 



Digi-Ke,v 113 87 

Digital Research Computers ........ 1 14 93 

ESI . 75 — 

Elect i-onic Technology Today . . . 76, CD 10 — 

Electronics Book Club 39 184 

Elephant Electronics 77 193 

Esofl Software CD16 — 

Etronix 28,91 110 

Flrestik II 93 — 

Fluke Manufacturing . . 1 7 96 

Eordham Radio CV4 126 

Vox Antennas 86 201 

Grantham College of Engineering .... 68 78 

HWSams ...28 185 

Hameg 89 188,189 

lleath 33 199 

Intek Electronics 76 206 

J&W 112 198 

JDK Instruments 13 92 

JDR Microdevices 1 04. 105 202 

JDR Microdevices 106,107 102 

JDR Microdevices 108 183 

Jameco 100.10! 66 

Jensen Tools 77 194,203 

Joseph Electronics. . 15 103 



MCM Electronics 109 

Mark V. Electronics . , 1 02 

McCraw Hill Book Club 80 

McGraw HD1/(CED) 31 

Mercer 25 

Microproessors UnJtd. CD16 

NRI ..8 

Omnitron 36 

Pacific Cable 97 

Probemaster 7 

RAC Electronics 5,23 

RCA D&SP 16 

Radio Shack 99 

Sulcn Enterprises 91 

Sencore 35,37 

Siber Ilegner 14 

Simpson CD4 

Star Circuits 77 

Tektronix CV2 

Transleteronic 90 

Trio-Kenwood 85 

United Electronic Supply 87 

W.S.Jenks 26 

Wavetek 24 

Wm B Allen 32 



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THE NEW 65/9028 VT 
ANSI VIDEO TERMINAL BOARD! 

* FROM LINGER ENTERPRISES * 
A second generation, low cost, high performance, mini sized, 
single board for making your own RS232 Video Terminal. Use 
as a computer console or with a MODEM for hookup to any of 
the telephone-line computer services. 



FEATURES; 

* Uses the new SMC 9028 Video 
Controller Chip coupled with a 
6502A CPU. 

* RS-232 at 16 Baud Rates from 50 
to 19,200 

* On board printer port! 

* 24 X 80 formal (50/60 Hi). 

* For 15,750 Hi (Horiz.) monitors. 

* 3 Terminal Modes: H-19. ADM3A. 
and ANSI X 3.64-1970 

* Wide and thin-line graphics. 

* White characters on black back- 
ground or reversed. 

* Character Attributes: De-lnten, 
Inverse or Underline. 

+ Low Power: 5VDC @ .7A, - 12VDC 
@ 20MA. 

* Mini size: 6.5 X 5 inches. 

* Composite or split video. 

* 5 X 8 Dot Matrix characters 
(U/L case). 

* Answer back capability. 

* Battery backed up status memory. 

* For ASCII parallel keyboard. 



MICRO SIZE! 




*a 



SQQ95 

^^ (Full Kit) 



SOURCE DISKETTE: 

PC/XT FORMAT 

5% IN. $15 



ADD S40 FOR A&T 



Digital Research Computers 

(OF TEXAS) 
P.O. BOX 381450 • DUNCANVILLE TX 75138 • (214) 225-2309 



Call or write for a tree catalog on Z-80 or 6809 Single Board 
Computers, SS-50 Boards, and other S-100 products. 



TERMS- Add S3. 00 postage. We pay balance. Order* under 515 add 75c handling. No 
C.O.O. We accept Visa and MasterCard. Tenas Res. add 5-1/8°: Taj. Foreign order* 
f except Canada) add 20>. P & H. Ordtrs over SSfj add Ssr: lor insurance. 




EQUALIZER 

• The ultimate non-lethal defense 
weapon, 

• In five seconds can immobilize your 
attacker, even through heavy clothing. 

■ Discharges over forty thousand volts 
of electricity from a nine volt nickel- 
cadmium battery. 

• S39.95,Mass 5% sales tax, $3.00 
shipping and handling. 

1-800-522-2636 



FOR ORDERS ONLY 

617-871-5611 
FOR INFORMATION 



Cameo Enterprises, Inc. 

P.O. Box 63, Accord, MA 02018 



CIRCLE 89 ON FREE INFORMATION CARD 



Gernshack Publications, Inc. 
500-B Bi-County Blvd. 
Farmingdalc, NY 11 735 
(516) 293-3000 
Pre si den I: Larry Sleekier 
Vice President: Calhy Sleekier 

For Advertising ONLY 
516-293-3000 
Larry Steckler 

publisher 
Arline Fishman 

advertising director 
Shelli Weinman 

advertising associate 
Lisa Strassman 

credit manager 
Christina Estrada 

advertising assistant 

SALES OFFICES 

EAST/SOUTHEAST 

Stanley Levitan 

Eastern Sales Manager 

Radio- Electronics 

259-23 57th Avenue 

Little Neck, NY 11362 

718-42B-6037, 516-293-3000 

MIDWEST/ 

Texas/A rkansas/Okla . 

Ralph Bergen 

Midwest Sales Manager 

Radio-Electronics 

540 Frontage Road— Suite 339 

Norlhfield, IL 60O93 

312-446-1444 

PACIFIC COAST; 

Mountain Stales 

Marvin Green 

Pacific Sales Manager 

Radio-Electronics 

I5335 Morrison St.— Suite 227 

Sherman Oaks, CA 91403 

818-986-2001 






A Successful Union 
Of Traditional And 
Contemporary Design 

The beauty, charm, simplicity of the Oak File Cabinet and 
the comfortable modern style of the Back Chair are more 
than just complementary pieces of furniture. They're 
handsome pieces which perform necessary functions in 
your home or business. Whether they stand united or alone 
they add a special dimension to your living area. 

An Opulent Oak File 

The two drawer oak file is made of solid wood with a beautifully 
polished oak veneer surface. Its pleasing simple lines blend with any 
interior bringing back the warmth and tradition of its early American 
counterparts. This handsome organizer has drawers which are 13 
inches deep which fits standard files hanging from steel rails. 
Dimensions: 28- 1 /4"H x 1 6-1 /4"W x 1 7"D. ^ AAap 

Model $fcQ95 





CF-22 



Discover The Comfort Of The Back Chair 

Delight in the comfort and mobility of the Adjustable Back Chair with 
Casters. The Back Chair helps alleviate the discomfort of the 
conventional chair by changing the stress points on the body. Instead of 
forcing your lower back to support your weight by sitting at a 90° 
angle, the Back Chair balances your weight proportionally through your 
lower body and legs. In this new position your spine straightens naturally; 
you're able to relax and concentrate more efficiently. The Back Chair Is 
user friendly and a viable alternative for those long hours at the 
computer, typewriter, desk or drawing board. 
The seat can be raised or lowered to 
accommodate each member of your 
household or business. Its handsome oakj 
veneer finish allows it to blend with any 
decor. 

Model CH-97 



SEND UN- 

ORDER iO: VfJ 260 Motor Parkway, Hauppauge, NY 11788 

□ Please send me Back Cholr(s) at S39.95 ea. 

Add S5.50 shipping charge for each piece. Total 



.J Please send me Oak Filets) at $89.95 ea. 

Add SIO.SO shipping charge (or each piece. Total 



□ My Check or Money Order is Enclosed. 
D Charge My Credit Card □ Visa 

Card * 

Signature 

Telephone: ( ) 

Name 



D MasterCard 



DAmex 



Exp. Date. 



State. 



Phone Orders Call Toll FREE out ot state BOO-645-9152 
nys Toll FREE 800-832-1446 ext. 42 




We Accept Visa, MasterCard 
and American Express. 




Model DCM-602 

$6995 

3 1 /2 Digit Capacitance Meter 

8 ranges with full scale values to 2000 uF 
FEATURES • Broad test range - 1 pF to 
2000 uF • LSI circuit provides high 

reliability and durability • Lower power 
consumption • Crystal time base 

• Protected from charged capacitors 

• Frequency range ■ 800 Hz to 8 Hz 



$48 7 s 



$7995 



7 functions, 32 ranges. 
Transistor measurement 
included. 



Model DVM-636 

$62 75 

8 functions, 37 ranges. 
Capacitance measurement 
included. 
3V2 Digital Multimeters 

FEATURES • DC Voltage 100 uV - 1000 V • AC Voltage 100 uV ■ 750 V • AC/DC Current 
200 uA - 10 Amps • Resistance 20 Megohms • Capacitance (DVM 636/638) 1 pF - 20 uF 
• Overload Protection • Auto-decimal LCD readout • Polarity indication • 300 hour 
battery life with 9V transistor battery • Low battery indication 



1 1 functions, 38 ranges. 
Includes logic level detector, 
audible visual continuity, 
capacitance and conductance 
measurement. 



ASK FOR FREE CATALOG. 

Money orders, checks accepted. C.O.D.'s require 25% deposit. 

Fordham 

260 Motor Parkway, Hauppauge, NY 1 1 788 



Toll Free 

800-645-9518 

In NY State 800-832-1446 



Service & Shipping Charge Schedule 

Caininenta! U.S.A. 

FOR ORDERS ADD 

S25-S10O S<!50 

S101-S250 S6O0 

$251-500 saoo 

5501-750 . 510.50 

$751-1.000 512.50 

S1.001-150O , . 516.50 

S1 .501 -2000 S2000 

S2.0O1 and Ud. . 52500